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Algorithms - RSA

Functions

Name
int wc_SetKeyUsage(Cert * cert, const char * value)
This function allows you to set the key usage using a comma delimited string of tokens. Accepted tokens are: digitalSignature, nonRepudiation, contentCommitment, keyCertSign, cRLSign, dataEncipherment, keyAgreement, keyEncipherment, encipherOnly, decipherOnly. Example: "digitalSignature,nonRepudiation" nonRepudiation and contentCommitment are for the same usage.
int wc_InitRsaKey(RsaKey * key, void * heap)
This function initializes a provided RsaKey struct. It also takes in a heap identifier, for use with user defined memory overrides (see XMALLOC, XFREE, XREALLOC).
int wc_InitRsaKey_Id(RsaKey * key, unsigned char * id, int len, void * heap, int devId)
This function initializes a provided RsaKey struct. The id and len are used to identify the key on the device while the devId identifies the device. It also takes in a heap identifier, for use with user defined memory overrides (see XMALLOC, XFREE, XREALLOC).
int wc_RsaSetRNG(RsaKey * key, WC_RNG * rng)
This function associates RNG with Key. It is needed when WC_RSA_BLINDING is enabled.
int wc_FreeRsaKey(RsaKey * key)
This function frees a provided RsaKey struct using mp_clear.
int wc_RsaDirect(byte * in, word32 inLen, byte * out, word32 * outSz, RsaKey * key, int type, WC_RNG * rng)
Function that does the RSA operation directly with no padding. The input size must match key size. Typically this is used when padding is already done on the RSA input.
int wc_RsaPublicEncrypt(const byte * in, word32 inLen, byte * out, word32 outLen, RsaKey * key, WC_RNG * rng)
This function encrypts a message from in and stores the result in out. It requires an initialized public key and a random number generator. As a side effect, this function will return the bytes written to out in outLen.
int wc_RsaPrivateDecryptInline(byte * in, word32 inLen, byte ** out, RsaKey * key)
This functions is utilized by the wc_RsaPrivateDecrypt function for decrypting.
int wc_RsaPrivateDecrypt(const byte * in, word32 inLen, byte * out, word32 outLen, RsaKey * key)
This functions provides private RSA decryption.
int wc_RsaSSL_Sign(const byte * in, word32 inLen, byte * out, word32 outLen, RsaKey * key, WC_RNG * rng)
Signs the provided array with the private key.
int wc_RsaSSL_VerifyInline(byte * in, word32 inLen, byte ** out, RsaKey * key)
Used to verify that the message was signed by RSA key. The output uses the same byte array as the input.
int wc_RsaSSL_Verify(const byte * in, word32 inLen, byte * out, word32 outLen, RsaKey * key)
Used to verify that the message was signed by key.
int wc_RsaPSS_Sign(const byte * in, word32 inLen, byte * out, word32 outLen, enum wc_HashType hash, int mgf, RsaKey * key, WC_RNG * rng)
Signs the provided array with the private key.
int wc_RsaPSS_Verify(byte * in, word32 inLen, byte * out, word32 outLen, enum wc_HashType hash, int mgf, RsaKey * key)
Decrypt input signature to verify that the message was signed by key. The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.
int wc_RsaPSS_VerifyInline(byte * in, word32 inLen, byte ** out, enum wc_HashType hash, int mgf, RsaKey * key)
Decrypt input signature to verify that the message was signed by RSA key. The output uses the same byte array as the input. The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.
int wc_RsaPSS_VerifyCheck(byte * in, word32 inLen, byte * out, word32 outLen, const byte * digest, word32 digestLen, enum wc_HashType hash, int mgf, RsaKey * key)
Verify the message signed with RSA-PSS. Salt length is equal to hash length. The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.
int wc_RsaPSS_VerifyCheck_ex(byte * in, word32 inLen, byte * out, word32 outLen, const byte * digest, word32 digestLen, enum wc_HashType hash, int mgf, int saltLen, RsaKey * key)
Verify the message signed with RSA-PSS. The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.
int wc_RsaPSS_VerifyCheckInline(byte * in, word32 inLen, byte ** out, const byte * digest, word32 digentLen, enum wc_HashType hash, int mgf, RsaKey * key)
Verify the message signed with RSA-PSS. The input buffer is reused for the output buffer. Salt length is equal to hash length.
int wc_RsaPSS_VerifyCheckInline_ex(byte * in, word32 inLen, byte ** out, const byte * digest, word32 digentLen, enum wc_HashType hash, int mgf, int saltLen, RsaKey * key)
Verify the message signed with RSA-PSS. The input buffer is reused for the output buffer. The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.
int wc_RsaPSS_CheckPadding(const byte * in, word32 inLen, byte * sig, word32 sigSz, enum wc_HashType hashType)
Checks the PSS data to ensure that the signature matches. Salt length is equal to hash length. The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.
int wc_RsaPSS_CheckPadding_ex(const byte * in, word32 inLen, byte * sig, word32 sigSz, enum wc_HashType hashType, int saltLen, int bits)
Checks the PSS data to ensure that the signature matches. Salt length is equal to hash length.
int wc_RsaEncryptSize(RsaKey * key)
Returns the encryption size for the provided key structure.
int wc_RsaPrivateKeyDecode(const byte * input, word32 * inOutIdx, RsaKey * key, word32 inSz)
This function parses a DER-formatted RSA private key, extracts the private key and stores it in the given RsaKey structure. It also sets the distance parsed in idx.
int wc_RsaPublicKeyDecode(const byte * input, word32 * inOutIdx, RsaKey * key, word32 inSz)
This function parses a DER-formatted RSA public key, extracts the public key and stores it in the given RsaKey structure. It also sets the distance parsed in idx.
int wc_RsaPublicKeyDecodeRaw(const byte * n, word32 nSz, const byte * e, word32 eSz, RsaKey * key)
This function decodes the raw elements of an RSA public key, taking in the public modulus (n) and exponent (e). It stores these raw elements in the provided RsaKey structure, allowing one to use them in the encryption/decryption process.
int wc_RsaKeyToDer(RsaKey * key, byte * output, word32 inLen)
This function converts an RsaKey key to DER format. The result is written to output and it returns the number of bytes written.
int wc_RsaPublicEncrypt_ex(const byte * in, word32 inLen, byte * out, word32 outLen, RsaKey * key, WC_RNG * rng, int type, enum wc_HashType hash, int mgf, byte * label, word32 labelSz)
This function performs RSA encrypt while allowing the choice of which padding to use.
int wc_RsaPrivateDecrypt_ex(const byte * in, word32 inLen, byte * out, word32 outLen, RsaKey * key, int type, enum wc_HashType hash, int mgf, byte * label, word32 labelSz)
This function uses RSA to decrypt a message and gives the option of what padding type.
int wc_RsaPrivateDecryptInline_ex(byte * in, word32 inLen, byte ** out, RsaKey * key, int type, enum wc_HashType hash, int mgf, byte * label, word32 labelSz)
This function uses RSA to decrypt a message inline and gives the option of what padding type. The in buffer will contain the decrypted message after being called and the out byte pointer will point to the location in the “in” buffer where the plain text is.
int wc_RsaFlattenPublicKey(RsaKey * key, byte * e, word32 * eSz, byte * n, word32 * nSz)
Flattens the RsaKey structure into individual elements (e, n) used for the RSA algorithm.
int wc_RsaKeyToPublicDer(RsaKey * key, byte * output, word32 inLen)
Convert Rsa Public key to DER format. Writes to output, and returns count of bytes written.
int wc_RsaKeyToPublicDer_ex(RsaKey * key, byte * output, word32 inLen, int with_header)
Convert RSA Public key to DER format. Writes to output, and returns count of bytes written. If with_header is 0 then only the ( seq + n + e) is returned in ASN.1 DER format and will exclude the header.
int wc_MakeRsaKey(RsaKey * key, int size, long e, WC_RNG * rng)
This function generates a RSA private key of length size (in bits) and given exponent (e). It then stores this key in the provided RsaKey structure, so that it may be used for encryption/decryption. A secure number to use for e is 65537. size is required to be greater than RSA_MIN_SIZE and less than RSA_MAX_SIZE. For this function to be available, the option WOLFSSL_KEY_GEN must be enabled at compile time. This can be accomplished with –enable-keygen if using ./configure.
int wc_RsaSetNonBlock(RsaKey * key, RsaNb * nb)
This function sets the non-blocking RSA context. When a RsaNb context is set it enables fast math based non-blocking exptmod, which splits the RSA function into many smaller operations. Enabled when WC_RSA_NONBLOCK is defined.
int wc_RsaSetNonBlockTime(RsaKey * key, word32 maxBlockUs, word32 cpuMHz)
This function configures the maximum amount of blocking time in microseconds. It uses a pre_computed table (see tfm.c exptModNbInst) along with the CPU speed in megahertz to determine if the next operation can be completed within the maximum blocking time provided. Enabled when WC_RSA_NONBLOCK_TIME is defined.

Functions Documentation

function wc_SetKeyUsage

int wc_SetKeyUsage(
    Cert * cert,
    const char * value
)

This function allows you to set the key usage using a comma delimited string of tokens. Accepted tokens are: digitalSignature, nonRepudiation, contentCommitment, keyCertSign, cRLSign, dataEncipherment, keyAgreement, keyEncipherment, encipherOnly, decipherOnly. Example: "digitalSignature,nonRepudiation" nonRepudiation and contentCommitment are for the same usage.

Parameters:

  • cert Pointer to initialized Cert structure.
  • value Comma delimited string of tokens to set usage.

See:

Return:

  • 0 Success
  • BAD_FUNC_ARG Returned when either arg is null.
  • MEMORY_E Returned when there is an error allocating memory.
  • KEYUSAGE_E Returned if an unrecognized token is entered.

Example

Cert cert;
wc_InitCert(&cert);

if(wc_SetKeyUsage(&cert, "cRLSign,keyCertSign") != 0)
{
    // Handle error
}

function wc_InitRsaKey

int wc_InitRsaKey(
    RsaKey * key,
    void * heap
)

This function initializes a provided RsaKey struct. It also takes in a heap identifier, for use with user defined memory overrides (see XMALLOC, XFREE, XREALLOC).

Parameters:

  • key pointer to the RsaKey structure to initialize
  • heap pointer to a heap identifier, for use with memory overrides, allowing custom handling of memory allocation. This heap will be the default used when allocating memory for use with this RSA object

See:

Return:

  • 0 Returned upon successfully initializing the RSA structure for use with encryption and decryption
  • BAD_FUNC_ARGS Returned if the RSA key pointer evaluates to NULL

The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.

Example

RsaKey enc;
int ret;
ret = wc_InitRsaKey(&enc, NULL); // not using heap hint. No custom memory
if ( ret != 0 ) {
    // error initializing RSA key
}

function wc_InitRsaKey_Id

int wc_InitRsaKey_Id(
    RsaKey * key,
    unsigned char * id,
    int len,
    void * heap,
    int devId
)

This function initializes a provided RsaKey struct. The id and len are used to identify the key on the device while the devId identifies the device. It also takes in a heap identifier, for use with user defined memory overrides (see XMALLOC, XFREE, XREALLOC).

Parameters:

  • key pointer to the RsaKey structure to initialize
  • id identifier of key on device
  • len length of identifier in bytes
  • heap pointer to a heap identifier, for use with memory overrides, allowing custom handling of memory allocation. This heap will be the default used when allocating memory for use with this RSA object
  • devId ID to use with crypto callbacks or async hardware. Set to INVALID_DEVID (-2) if not used

See:

Return:

  • 0 Returned upon successfully initializing the RSA structure for use with encryption and decryption
  • BAD_FUNC_ARGS Returned if the RSA key pointer evaluates to NULL
  • BUFFER_E Returned if len is less than 0 or greater than RSA_MAX_ID_LEN.

The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.

Example

RsaKey enc;
unsigned char* id = (unsigned char*)"RSA2048";
int len = 6;
int devId = 1;
int ret;
ret = wc_CryptoDev_RegisterDevice(devId, wc_Pkcs11_CryptoDevCb,
                                  &token);
if ( ret != 0) {
    // error associating callback and token with device id
}
ret = wc_InitRsaKey_Id(&enc, id, len, NULL, devId); // not using heap hint
if ( ret != 0 ) {
    // error initializing RSA key
}

function wc_RsaSetRNG

int wc_RsaSetRNG(
    RsaKey * key,
    WC_RNG * rng
)

This function associates RNG with Key. It is needed when WC_RSA_BLINDING is enabled.

Parameters:

  • key pointer to the RsaKey structure to be associated
  • rng pointer to the WC_RNG structure to associate with

See:

Return:

  • 0 Returned upon success
  • BAD_FUNC_ARGS Returned if the RSA key, rng pointer evaluates to NULL

Example

ret = wc_InitRsaKey(&key, NULL);
if (ret == 0) {
    ret = wc_InitRng(&rng);
} else return -1;
if (ret == 0) {
    ret = wc_RsaSetRNG(&key, &rng);

function wc_FreeRsaKey

int wc_FreeRsaKey(
    RsaKey * key
)

This function frees a provided RsaKey struct using mp_clear.

Parameters:

  • key pointer to the RsaKey structure to free

See: wc_InitRsaKey

Return: 0 Returned upon successfully freeing the key

Example

RsaKey enc;
wc_InitRsaKey(&enc, NULL); // not using heap hint. No custom memory
... set key, do encryption

wc_FreeRsaKey(&enc);

function wc_RsaDirect

int wc_RsaDirect(
    byte * in,
    word32 inLen,
    byte * out,
    word32 * outSz,
    RsaKey * key,
    int type,
    WC_RNG * rng
)

Function that does the RSA operation directly with no padding. The input size must match key size. Typically this is used when padding is already done on the RSA input.

Parameters:

  • in buffer to do operation on
  • inLen length of input buffer
  • out buffer to hold results
  • outSz gets set to size of result buffer. Should be passed in as length of out buffer. If the pointer "out" is null then outSz gets set to the expected buffer size needed and LENGTH_ONLY_E gets returned.
  • key initialized RSA key to use for encrypt/decrypt
  • type if using private or public key (RSA_PUBLIC_ENCRYPT, RSA_PUBLIC_DECRYPT, RSA_PRIVATE_ENCRYPT, RSA_PRIVATE_DECRYPT)
  • rng initialized WC_RNG struct

See:

Return:

  • size On successfully encryption the size of the encrypted buffer is returned
  • RSA_BUFFER_E RSA buffer error, output too small or input too large

Example

int ret;
WC_RNG rng;
RsaKey key;
byte  in[256];
byte out[256];
word32 outSz = (word32)sizeof(out);
…

ret = wc_RsaDirect(in, (word32)sizeof(in), out, &outSz, &key,
    RSA_PRIVATE_ENCRYPT, &rng);
if (ret < 0) {
    //handle error
}

function wc_RsaPublicEncrypt

int wc_RsaPublicEncrypt(
    const byte * in,
    word32 inLen,
    byte * out,
    word32 outLen,
    RsaKey * key,
    WC_RNG * rng
)

This function encrypts a message from in and stores the result in out. It requires an initialized public key and a random number generator. As a side effect, this function will return the bytes written to out in outLen.

Parameters:

  • in pointer to a buffer containing the input message to encrypt
  • inLen the length of the message to encrypt
  • out pointer to the buffer in which to store the output ciphertext
  • outLen the length of the output buffer
  • key pointer to the RsaKey structure containing the public key to use for encryption
  • rng The RNG structure with which to generate random block padding

See: wc_RsaPrivateDecrypt

Return:

  • Success Upon successfully encrypting the input message, returns 0 for success and less than zero for failure. Also returns the number bytes written to out by storing the value in outLen
  • BAD_FUNC_ARG Returned if any of the input parameters are invalid
  • RSA_BUFFER_E Returned if the output buffer is too small to store the ciphertext
  • RNG_FAILURE_E Returned if there is an error generating a random block using the provided RNG structure
  • MP_INIT_E May be returned if there is an error in the math library used while encrypting the message
  • MP_READ_E May be returned if there is an error in the math library used while encrypting the message
  • MP_CMP_E May be returned if there is an error in the math library used while encrypting the message
  • MP_INVMOD_E May be returned if there is an error in the math library used while encrypting the message
  • MP_EXPTMOD_E May be returned if there is an error in the math library used while encrypting the message
  • MP_MOD_E May be returned if there is an error in the math library used while encrypting the message
  • MP_MUL_E May be returned if there is an error in the math library used while encrypting the message
  • MP_ADD_E May be returned if there is an error in the math library used while encrypting the message
  • MP_MULMOD_E May be returned if there is an error in the math library used while encrypting the message
  • MP_TO_E May be returned if there is an error in the math library used while encrypting the message
  • MP_MEM May be returned if there is an error in the math library used while encrypting the message
  • MP_ZERO_E May be returned if there is an error in the math library used while encrypting the message

Example

RsaKey pub;
int ret = 0;
byte n[] = { // initialize with received n component of public key };
byte e[] = { // initialize with received e component of public key };
byte msg[] = { // initialize with plaintext of message to encrypt };
byte cipher[256]; // 256 bytes is large enough to store 2048 bit RSA
ciphertext

wc_InitRsaKey(&pub, NULL); // not using heap hint. No custom memory
wc_RsaPublicKeyDecodeRaw(n, sizeof(n), e, sizeof(e), &pub);
// initialize with received public key parameters
ret = wc_RsaPublicEncrypt(msg, sizeof(msg), out, sizeof(out), &pub, &rng);
if ( ret != 0 ) {
    // error encrypting message
}

function wc_RsaPrivateDecryptInline

int wc_RsaPrivateDecryptInline(
    byte * in,
    word32 inLen,
    byte ** out,
    RsaKey * key
)

This functions is utilized by the wc_RsaPrivateDecrypt function for decrypting.

Parameters:

  • in The byte array to be decrypted.
  • inLen The length of in.
  • out The byte array for the decrypted data to be stored.
  • key The key to use for decryption.

See: wc_RsaPrivateDecrypt

Return:

  • Success Length of decrypted data.
  • RSA_PAD_E RsaUnPad error, bad formatting

Example

none

function wc_RsaPrivateDecrypt

int wc_RsaPrivateDecrypt(
    const byte * in,
    word32 inLen,
    byte * out,
    word32 outLen,
    RsaKey * key
)

This functions provides private RSA decryption.

Parameters:

  • in The byte array to be decrypted.
  • inLen The length of in.
  • out The byte array for the decrypted data to be stored.
  • outLen The length of out.
  • key The key to use for decryption.

See:

Return:

  • Success length of decrypted data.
  • MEMORY_E -125, out of memory error
  • BAD_FUNC_ARG -173, Bad function argument provided

Example

ret = wc_RsaPublicEncrypt(in, inLen, out, sizeof(out), &key, &rng);
if (ret < 0) {
    return -1;
}
ret = wc_RsaPrivateDecrypt(out, ret, plain, sizeof(plain), &key);
if (ret < 0) {
    return -1;
}

function wc_RsaSSL_Sign

int wc_RsaSSL_Sign(
    const byte * in,
    word32 inLen,
    byte * out,
    word32 outLen,
    RsaKey * key,
    WC_RNG * rng
)

Signs the provided array with the private key.

Parameters:

  • in The byte array to be encrypted.
  • inLen The length of in.
  • out The byte array for the encrypted data to be stored.
  • outLen The length of out.
  • key The key to use for encryption.
  • RNG The RNG struct to use for random number purposes.

See: wc_RsaPad

Return: RSA_BUFFER_E: -131, RSA buffer error, output too small or input too large

Example

ret = wc_RsaSSL_Sign(in, inLen, out, sizeof(out), &key, &rng);
if (ret < 0) {
    return -1;
}
memset(plain, 0, sizeof(plain));
ret = wc_RsaSSL_Verify(out, ret, plain, sizeof(plain), &key);
if (ret < 0) {
    return -1;
}
if (ret != inLen) {
    return -1;
}
if (XMEMCMP(in, plain, ret) != 0) {
    return -1;
}

function wc_RsaSSL_VerifyInline

int wc_RsaSSL_VerifyInline(
    byte * in,
    word32 inLen,
    byte ** out,
    RsaKey * key
)

Used to verify that the message was signed by RSA key. The output uses the same byte array as the input.

Parameters:

  • in Byte array to be decrypted.
  • inLen Length of the buffer input.
  • out Pointer to a pointer for decrypted information.
  • key RsaKey to use.

See:

Return:

  • 0 Length of text.

  • <0 An error occurred.

Example

RsaKey key;
WC_RNG rng;
int ret = 0;
long e = 65537; // standard value to use for exponent
wc_InitRsaKey(&key, NULL); // not using heap hint. No custom memory
wc_InitRng(&rng);
wc_MakeRsaKey(&key, 2048, e, &rng);

byte in[] = { // Initialize with some RSA encrypted information }
byte* out;
if(wc_RsaSSL_VerifyInline(in, sizeof(in), &out, &key) < 0)
{
    // handle error
}

function wc_RsaSSL_Verify

int wc_RsaSSL_Verify(
    const byte * in,
    word32 inLen,
    byte * out,
    word32 outLen,
    RsaKey * key
)

Used to verify that the message was signed by key.

Parameters:

  • in The byte array to be decrypted.
  • inLen The length of in.
  • out The byte array for the decrypted data to be stored.
  • outLen The length of out.
  • key The key to use for verification.

See: wc_RsaSSL_Sign

Return:

  • Success Length of text on no error.
  • MEMORY_E memory exception.

Example

ret = wc_RsaSSL_Sign(in, inLen, out, sizeof(out), &key, &rng);
if (ret < 0) {
    return -1;
}
memset(plain, 0, sizeof(plain));
ret = wc_RsaSSL_Verify(out, ret, plain, sizeof(plain), &key);
if (ret < 0) {
    return -1;
}
if (ret != inLen) {
    return -1;
}
if (XMEMCMP(in, plain, ret) != 0) {
    return -1;
}

function wc_RsaPSS_Sign

int wc_RsaPSS_Sign(
    const byte * in,
    word32 inLen,
    byte * out,
    word32 outLen,
    enum wc_HashType hash,
    int mgf,
    RsaKey * key,
    WC_RNG * rng
)

Signs the provided array with the private key.

Parameters:

  • in The byte array to be encrypted.
  • inLen The length of in.
  • out The byte array for the encrypted data to be stored.
  • outLen The length of out.
  • hash The hash type to be in message
  • mgf Mask Generation Function Identifiers
  • key The key to use for verification.

See:

Return: RSA_BUFFER_E: -131, RSA buffer error, output too small or input too large

Example

ret = wc_InitRsaKey(&key, NULL);
if (ret == 0) {
    ret = wc_InitRng(&rng);
} else return -1;
if (ret == 0) {
    ret = wc_RsaSetRNG(&key, &rng);
} else return -1;
if (ret == 0) {
        ret = wc_MakeRsaKey(&key, 2048, WC_RSA_EXPONENT, &rng);
} else return -1;

ret = wc_RsaPSS_Sign((byte*)szMessage, (word32)XSTRLEN(szMessage)+1,
        pSignature, sizeof(pSignature),
        WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key, &rng);
if (ret > 0 ){
    sz = ret;
} else return -1;

ret = wc_RsaPSS_Verify(pSignature, sz, pt, outLen,
        WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key);
if (ret <= 0)return -1;

wc_FreeRsaKey(&key);
wc_FreeRng(&rng);

function wc_RsaPSS_Verify

int wc_RsaPSS_Verify(
    byte * in,
    word32 inLen,
    byte * out,
    word32 outLen,
    enum wc_HashType hash,
    int mgf,
    RsaKey * key
)

Decrypt input signature to verify that the message was signed by key. The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.

Parameters:

  • in The byte array to be decrypted.
  • inLen The length of in.
  • out The byte array for the decrypted data to be stored.
  • outLen The length of out.
  • hash The hash type to be in message
  • mgf Mask Generation Function Identifiers
  • key The key to use for verification.

See:

Return:

  • Success Length of text on no error.
  • MEMORY_E memory exception.
  • MP_EXPTMOD_E - When using fastmath and FP_MAX_BITS not set to at least 2 times the keySize (Example when using 4096-bit key set FP_MAX_BITS to 8192 or greater value)

Example

ret = wc_InitRsaKey(&key, NULL);
if (ret == 0) {
    ret = wc_InitRng(&rng);
} else return -1;
if (ret == 0) {
    ret = wc_RsaSetRNG(&key, &rng);
} else return -1;
if (ret == 0) {
        ret = wc_MakeRsaKey(&key, 2048, WC_RSA_EXPONENT, &rng);
} else return -1;
ret = wc_RsaPSS_Sign((byte*)szMessage, (word32)XSTRLEN(szMessage)+1,
        pSignature, sizeof(pSignature),
        WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key, &rng);
if (ret > 0 ){
    sz = ret;
} else return -1;

ret = wc_RsaPSS_Verify(pSignature, sz, pt, outLen,
        WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key);
if (ret <= 0)return -1;

wc_FreeRsaKey(&key);
wc_FreeRng(&rng);

function wc_RsaPSS_VerifyInline

int wc_RsaPSS_VerifyInline(
    byte * in,
    word32 inLen,
    byte ** out,
    enum wc_HashType hash,
    int mgf,
    RsaKey * key
)

Decrypt input signature to verify that the message was signed by RSA key. The output uses the same byte array as the input. The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.

Parameters:

  • in Byte array to be decrypted.
  • inLen Length of the buffer input.
  • out Pointer to address containing the PSS data.
  • hash The hash type to be in message
  • mgf Mask Generation Function Identifiers
  • key RsaKey to use.

See:

Return:

  • 0 Length of text.

  • <0 An error occurred.

Example 

ret = wc_InitRsaKey(&key, NULL);
if (ret == 0) {
    ret = wc_InitRng(&rng);
} else return -1;
if (ret == 0) {
    ret = wc_RsaSetRNG(&key, &rng);
} else return -1;
if (ret == 0) {
        ret = wc_MakeRsaKey(&key, 2048, WC_RSA_EXPONENT, &rng);
} else return -1;
ret = wc_RsaPSS_Sign(digest, digestSz, pSignature, pSignatureSz,
        WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key, &rng);
if (ret > 0 ){
    sz = ret;
} else return -1;

ret = wc_RsaPSS_VerifyInline(pSignature, sz, pt,
        WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key);
if (ret <= 0)return -1;

wc_FreeRsaKey(&key);
wc_FreeRng(&rng);

function wc_RsaPSS_VerifyCheck

int wc_RsaPSS_VerifyCheck(
    byte * in,
    word32 inLen,
    byte * out,
    word32 outLen,
    const byte * digest,
    word32 digestLen,
    enum wc_HashType hash,
    int mgf,
    RsaKey * key
)

Verify the message signed with RSA-PSS. Salt length is equal to hash length. The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.

Parameters:

  • in The byte array to be decrypted.
  • inLen The length of in.
  • out Pointer to address containing the PSS data.
  • outLen The length of out.
  • digest Hash of the data that is being verified.
  • digestLen Length of hash.
  • hash Hash algorithm.
  • mgf Mask generation function.
  • key Public RSA key.

See:

Return:

  • the length of the PSS data on success and negative indicates failure.
  • MEMORY_E memory exception.

Example

ret = wc_InitRsaKey(&key, NULL);
if (ret == 0) {
    ret = wc_InitRng(&rng);
} else return -1;
if (ret == 0) {
    ret = wc_RsaSetRNG(&key, &rng);
} else return -1;
if (ret == 0) {
        ret = wc_MakeRsaKey(&key, 2048, WC_RSA_EXPONENT, &rng);
} else return -1;

if (ret == 0) {
    digestSz = wc_HashGetDigestSize(WC_HASH_TYPE_SHA256);
    ret = wc_Hash(WC_HASH_TYPE_SHA256, message, sz, digest, digestSz);
} else return -1;

if (ret == 0) {
    ret = wc_RsaPSS_Sign(digest, digestSz, pSignature, pSignatureSz,
            WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key, &rng);
    if (ret > 0 ){
        sz = ret;
    } else return -1;
} else return -1;
if (ret == 0) {
    ret = wc_RsaPSS_VerifyCheck(pSignature, sz, pt, outLen,
            digest, digestSz, WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key);
        if (ret <= 0) return -1;
} else return -1;

wc_FreeRsaKey(&key);
wc_FreeRng(&rng);

function wc_RsaPSS_VerifyCheck_ex

int wc_RsaPSS_VerifyCheck_ex(
    byte * in,
    word32 inLen,
    byte * out,
    word32 outLen,
    const byte * digest,
    word32 digestLen,
    enum wc_HashType hash,
    int mgf,
    int saltLen,
    RsaKey * key
)

Verify the message signed with RSA-PSS. The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.

Parameters:

  • in The byte array to be decrypted.
  • inLen The length of in.
  • out Pointer to address containing the PSS data.
  • outLen The length of out.
  • digest Hash of the data that is being verified.
  • digestLen Length of hash.
  • hash Hash algorithm.
  • mgf Mask generation function.
  • saltLen Length of salt used. RSA_PSS_SALT_LEN_DEFAULT (-1) indicates salt length is the same as the hash length. RSA_PSS_SALT_LEN_DISCOVER indicates salt length is determined from the data.
  • key Public RSA key.

See:

Return:

  • the length of the PSS data on success and negative indicates failure.
  • MEMORY_E memory exception.

Example

ret = wc_InitRsaKey(&key, NULL);
if (ret == 0) {
    ret = wc_InitRng(&rng);
} else return -1;
if (ret == 0) {
    ret = wc_RsaSetRNG(&key, &rng);
} else return -1;
if (ret == 0) {
        ret = wc_MakeRsaKey(&key, 2048, WC_RSA_EXPONENT, &rng);
} else return -1;

if (ret == 0) {
    digestSz = wc_HashGetDigestSize(WC_HASH_TYPE_SHA256);
    ret = wc_Hash(WC_HASH_TYPE_SHA256, message, sz, digest, digestSz);
} else return -1;

if (ret == 0) {
    ret = wc_RsaPSS_Sign(digest, digestSz, pSignature, pSignatureSz,
            WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key, &rng);
    if (ret > 0 ){
        sz = ret;
    } else return -1;
} else return -1;
if (ret == 0) {
    ret = wc_RsaPSS_VerifyCheck_ex(pSignature, sz, pt, outLen,
            digest, digestSz, WC_HASH_TYPE_SHA256, WC_MGF1SHA256, saltLen, &key);
        if (ret <= 0) return -1;
} else return -1;

wc_FreeRsaKey(&key);
wc_FreeRng(&rng);

function wc_RsaPSS_VerifyCheckInline

int wc_RsaPSS_VerifyCheckInline(
    byte * in,
    word32 inLen,
    byte ** out,
    const byte * digest,
    word32 digentLen,
    enum wc_HashType hash,
    int mgf,
    RsaKey * key
)

Verify the message signed with RSA-PSS. The input buffer is reused for the output buffer. Salt length is equal to hash length.

Parameters:

  • in The byte array to be decrypted.
  • inLen The length of in.
  • out The byte array for the decrypted data to be stored.
  • digest Hash of the data that is being verified.
  • digestLen Length of hash.
  • hash The hash type to be in message
  • mgf Mask Generation Function Identifiers
  • key The key to use for verification.

See:

Return: the length of the PSS data on success and negative indicates failure.

The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.

Example

ret = wc_InitRsaKey(&key, NULL);
if (ret == 0) {
    ret = wc_InitRng(&rng);
} else return -1;
if (ret == 0) {
    ret = wc_RsaSetRNG(&key, &rng);
} else return -1;
if (ret == 0) {
        ret = wc_MakeRsaKey(&key, 2048, WC_RSA_EXPONENT, &rng);
} else return -1;

if (ret == 0) {
    digestSz = wc_HashGetDigestSize(WC_HASH_TYPE_SHA256);
    ret = wc_Hash(WC_HASH_TYPE_SHA256, message, sz, digest, digestSz);
} else return -1;

if (ret == 0) {
    ret = wc_RsaPSS_Sign(digest, digestSz, pSignature, pSignatureSz,
            WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key, &rng);
    if (ret > 0 ){
        sz = ret;
    } else return -1;
} else return -1;
if (ret == 0) {
    ret = wc_RsaPSS_VerifyCheckInline(pSignature, sz, pt,
            digest, digestSz, WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key);
        if (ret <= 0) return -1;
} else return -1;

wc_FreeRsaKey(&key);
wc_FreeRng(&rng);

function wc_RsaPSS_VerifyCheckInline_ex

int wc_RsaPSS_VerifyCheckInline_ex(
    byte * in,
    word32 inLen,
    byte ** out,
    const byte * digest,
    word32 digentLen,
    enum wc_HashType hash,
    int mgf,
    int saltLen,
    RsaKey * key
)

Verify the message signed with RSA-PSS. The input buffer is reused for the output buffer. The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.

Parameters:

  • in The byte array to be decrypted.
  • inLen The length of in.
  • out The byte array for the decrypted data to be stored.
  • digest Hash of the data that is being verified.
  • digestLen Length of hash.
  • hash The hash type to be in message
  • mgf Mask Generation Function Identifiers
  • saltLen Length of salt used. RSA_PSS_SALT_LEN_DEFAULT (-1) indicates salt length is the same as the hash length. RSA_PSS_SALT_LEN_DISCOVER indicates salt length is determined from the data.
  • key The key to use for verification.

See:

Return: the length of the PSS data on success and negative indicates failure.

Example

ret = wc_InitRsaKey(&key, NULL);
if (ret == 0) {
    ret = wc_InitRng(&rng);
} else return -1;
if (ret == 0) {
    ret = wc_RsaSetRNG(&key, &rng);
} else return -1;
if (ret == 0) {
        ret = wc_MakeRsaKey(&key, 2048, WC_RSA_EXPONENT, &rng);
} else return -1;

if (ret == 0) {
    digestSz = wc_HashGetDigestSize(WC_HASH_TYPE_SHA256);
    ret = wc_Hash(WC_HASH_TYPE_SHA256, message, sz, digest, digestSz);
} else return -1;

if (ret == 0) {
    ret = wc_RsaPSS_Sign(digest, digestSz, pSignature, pSignatureSz,
            WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key, &rng);
    if (ret > 0 ){
        sz = ret;
    } else return -1;
} else return -1;
if (ret == 0) {
    ret = wc_RsaPSS_VerifyCheckInline_ex(pSignature, sz, pt,
            digest, digestSz, WC_HASH_TYPE_SHA256, WC_MGF1SHA256, saltLen, &key);
        if (ret <= 0) return -1;
} else return -1;

wc_FreeRsaKey(&key);
wc_FreeRng(&rng);

function wc_RsaPSS_CheckPadding

int wc_RsaPSS_CheckPadding(
    const byte * in,
    word32 inLen,
    byte * sig,
    word32 sigSz,
    enum wc_HashType hashType
)

Checks the PSS data to ensure that the signature matches. Salt length is equal to hash length. The key has to be associated with RNG by wc_RsaSetRNG when WC_RSA_BLINDING is enabled.

Parameters:

  • in Hash of the data that is being verified.
  • inSz Length of hash.
  • sig Buffer holding PSS data.
  • sigSz Size of PSS data.
  • hashType Hash algorithm.

See:

Return:

  • BAD_PADDING_E when the PSS data is invalid, BAD_FUNC_ARG when NULL is passed in to in or sig or inSz is not the same as the hash algorithm length and 0 on success.
  • MEMORY_E memory exception.

Example

ret = wc_InitRsaKey(&key, NULL);
if (ret == 0) {
    ret = wc_InitRng(&rng);
} else return -1;
if (ret == 0) {
    ret = wc_RsaSetRNG(&key, &rng);
} else return -1;
if (ret == 0) {
        ret = wc_MakeRsaKey(&key, 2048, WC_RSA_EXPONENT, &rng);
} else return -1;
if (ret == 0) {
    digestSz = wc_HashGetDigestSize(WC_HASH_TYPE_SHA256);
    ret = wc_Hash(WC_HASH_TYPE_SHA256, message, sz, digest, digestSz);
} else return -1;
ret = wc_RsaPSS_Sign(digest, digestSz, pSignature, sizeof(pSignature),
        WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key, &rng);
if (ret > 0 ){
    sz = ret;
} else return -1;

verify = wc_RsaPSS_Verify(pSignature, sz, out, outLen,
        WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key);
if (verify <= 0)return -1;

ret = wc_RsaPSS_CheckPadding(digest, digestSz, out, verify, hash);

wc_FreeRsaKey(&key);
wc_FreeRng(&rng);

function wc_RsaPSS_CheckPadding_ex

int wc_RsaPSS_CheckPadding_ex(
    const byte * in,
    word32 inLen,
    byte * sig,
    word32 sigSz,
    enum wc_HashType hashType,
    int saltLen,
    int bits
)

Checks the PSS data to ensure that the signature matches. Salt length is equal to hash length.

Parameters:

  • in Hash of the data that is being verified.
  • inSz Length of hash.
  • sig Buffer holding PSS data.
  • sigSz Size of PSS data.
  • hashType Hash algorithm.
  • saltLen Length of salt used. RSA_PSS_SALT_LEN_DEFAULT (-1) indicates salt length is the same as the hash length. RSA_PSS_SALT_LEN_DISCOVER indicates salt length is determined from the data.
  • bits Can be used to calculate salt size in FIPS case

See:

Return:

  • BAD_PADDING_E when the PSS data is invalid, BAD_FUNC_ARG when NULL is passed in to in or sig or inSz is not the same as the hash algorithm length and 0 on success.
  • MEMORY_E memory exception.

Example

ret = wc_InitRsaKey(&key, NULL);
if (ret == 0) {
    ret = wc_InitRng(&rng);
} else return -1;
if (ret == 0) {
    ret = wc_RsaSetRNG(&key, &rng);
} else return -1;
if (ret == 0) {
        ret = wc_MakeRsaKey(&key, 2048, WC_RSA_EXPONENT, &rng);
} else return -1;
if (ret == 0) {
    digestSz = wc_HashGetDigestSize(WC_HASH_TYPE_SHA256);
    ret = wc_Hash(WC_HASH_TYPE_SHA256, message, sz, digest, digestSz);
} else return -1;
ret = wc_RsaPSS_Sign(digest, digestSz, pSignature, sizeof(pSignature),
        WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key, &rng);
if (ret > 0 ){
    sz = ret;
} else return -1;

verify = wc_RsaPSS_Verify(pSignature, sz, out, outLen,
        WC_HASH_TYPE_SHA256, WC_MGF1SHA256, &key);
if (verify <= 0)return -1;

ret = wc_RsaPSS_CheckPadding_ex(digest, digestSz, out, verify, hash, saltLen, 0);

wc_FreeRsaKey(&key);
wc_FreeRng(&rng);

function wc_RsaEncryptSize

int wc_RsaEncryptSize(
    RsaKey * key
)

Returns the encryption size for the provided key structure.

Parameters:

  • key The key to use for verification.

See:

Return: Success Encryption size for the provided key structure.

Example

int sz = wc_RsaEncryptSize(&key);

function wc_RsaPrivateKeyDecode

int wc_RsaPrivateKeyDecode(
    const byte * input,
    word32 * inOutIdx,
    RsaKey * key,
    word32 inSz
)

This function parses a DER-formatted RSA private key, extracts the private key and stores it in the given RsaKey structure. It also sets the distance parsed in idx.

Parameters:

  • input pointer to the buffer containing the DER formatted private key to decode
  • inOutIdx pointer to the index in the buffer at which the key begins (usually 0). As a side effect of this function, inOutIdx will store the distance parsed through the input buffer
  • key pointer to the RsaKey structure in which to store the decoded private key
  • inSz size of the input buffer

See:

Return:

  • 0 Returned upon successfully parsing the private key from the DER encoded input
  • ASN_PARSE_E Returned if there is an error parsing the private key from the input buffer. This may happen if the input private key is not properly formatted according to ASN.1 standards
  • ASN_RSA_KEY_E Returned if there is an error reading the private key elements of the RSA key input

Example

RsaKey enc;
word32 idx = 0;
int ret = 0;
byte der[] = { // initialize with DER-encoded RSA private key };

wc_InitRsaKey(&enc, NULL); // not using heap hint. No custom memory
ret = wc_RsaPrivateKeyDecode(der, &idx, &enc, sizeof(der));
if( ret != 0 ) {
    // error parsing private key
}

function wc_RsaPublicKeyDecode

int wc_RsaPublicKeyDecode(
    const byte * input,
    word32 * inOutIdx,
    RsaKey * key,
    word32 inSz
)

This function parses a DER-formatted RSA public key, extracts the public key and stores it in the given RsaKey structure. It also sets the distance parsed in idx.

Parameters:

  • input pointer to the buffer containing the input DER-encoded RSA public key to decode
  • inOutIdx pointer to the index in the buffer at which the key begins (usually 0). As a side effect of this function, inOutIdx will store the distance parsed through the input buffer
  • key pointer to the RsaKey structure in which to store the decoded public key
  • inSz size of the input buffer

See: wc_RsaPublicKeyDecodeRaw

Return:

  • 0 Returned upon successfully parsing the public key from the DER encoded input
  • ASN_PARSE_E Returned if there is an error parsing the public key from the input buffer. This may happen if the input public key is not properly formatted according to ASN.1 standards
  • ASN_OBJECT_ID_E Returned if the ASN.1 Object ID does not match that of a RSA public key
  • ASN_EXPECT_0_E Returned if the input key is not correctly formatted according to ASN.1 standards
  • ASN_BITSTR_E Returned if the input key is not correctly formatted according to ASN.1 standards
  • ASN_RSA_KEY_E Returned if there is an error reading the public key elements of the RSA key input

Example

RsaKey pub;
word32 idx = 0;
int ret = 0;
byte der[] = { // initialize with DER-encoded RSA public key };

wc_InitRsaKey(&pub, NULL); // not using heap hint. No custom memory
ret = wc_RsaPublicKeyDecode(der, &idx, &pub, sizeof(der));
if( ret != 0 ) {
    // error parsing public key
}

function wc_RsaPublicKeyDecodeRaw

int wc_RsaPublicKeyDecodeRaw(
    const byte * n,
    word32 nSz,
    const byte * e,
    word32 eSz,
    RsaKey * key
)

This function decodes the raw elements of an RSA public key, taking in the public modulus (n) and exponent (e). It stores these raw elements in the provided RsaKey structure, allowing one to use them in the encryption/decryption process.

Parameters:

  • n pointer to a buffer containing the raw modulus parameter of the public RSA key
  • nSz size of the buffer containing n
  • e pointer to a buffer containing the raw exponent parameter of the public RSA key
  • eSz size of the buffer containing e
  • key pointer to the RsaKey struct to initialize with the provided public key elements

See: wc_RsaPublicKeyDecode

Return:

  • 0 Returned upon successfully decoding the raw elements of the public key into the RsaKey structure
  • BAD_FUNC_ARG Returned if any of the input arguments evaluates to NULL
  • MP_INIT_E Returned if there is an error initializing an integer for use with the multiple precision integer (mp_int) library
  • ASN_GETINT_E Returned if there is an error reading one of the provided RSA key elements, n or e

Example

RsaKey pub;
int ret = 0;
byte n[] = { // initialize with received n component of public key };
byte e[] = { // initialize with received e component of public key };

wc_InitRsaKey(&pub, NULL); // not using heap hint. No custom memory
ret = wc_RsaPublicKeyDecodeRaw(n, sizeof(n), e, sizeof(e), &pub);
if( ret != 0 ) {
    // error parsing public key elements
}

function wc_RsaKeyToDer

int wc_RsaKeyToDer(
    RsaKey * key,
    byte * output,
    word32 inLen
)

This function converts an RsaKey key to DER format. The result is written to output and it returns the number of bytes written.

Parameters:

  • key Initialized RsaKey structure.
  • output Pointer to output buffer.
  • inLen Size of output buffer.

See:

Return:

  • 0 Success, number of bytes written.

  • BAD_FUNC_ARG Returned if key or output is null, or if key->type is not RSA_PRIVATE, or if inLen isn't large enough for output buffer.
  • MEMORY_E Returned if there is an error allocating memory.

Example

byte* der;
// Allocate memory for der
int derSz = // Amount of memory allocated for der;
RsaKey key;
WC_RNG rng;
long e = 65537; // standard value to use for exponent
ret = wc_MakeRsaKey(&key, 2048, e, &rng); // generate 2048 bit long
private key
wc_InitRsaKey(&key, NULL);
wc_InitRng(&rng);
if(wc_RsaKeyToDer(&key, der, derSz) != 0)
{
    // Handle the error thrown
}

function wc_RsaPublicEncrypt_ex

int wc_RsaPublicEncrypt_ex(
    const byte * in,
    word32 inLen,
    byte * out,
    word32 outLen,
    RsaKey * key,
    WC_RNG * rng,
    int type,
    enum wc_HashType hash,
    int mgf,
    byte * label,
    word32 labelSz
)

This function performs RSA encrypt while allowing the choice of which padding to use.

Parameters:

  • in pointer to the buffer for encryption
  • inLen length of the buffer to encrypt
  • out encrypted msg created
  • outLen length of buffer available to hold encrypted msg
  • key initialized RSA key struct
  • rng initialized WC_RNG struct
  • type type of padding to use (WC_RSA_OAEP_PAD or WC_RSA_PKCSV15_PAD)
  • hash type of hash to use (choices can be found in hash.h)
  • mgf type of mask generation function to use
  • label an optional label to associate with encrypted message
  • labelSz size of the optional label used

See:

Return:

  • size On successfully encryption the size of the encrypted buffer is returned
  • RSA_BUFFER_E RSA buffer error, output too small or input too large

Example

WC_RNG rng;
RsaKey key;
byte in[] = “I use Turing Machines to ask questions”
byte out[256];
int ret;
…

ret = wc_RsaPublicEncrypt_ex(in, sizeof(in), out, sizeof(out), &key, &rng,
WC_RSA_OAEP_PAD, WC_HASH_TYPE_SHA, WC_MGF1SHA1, NULL, 0);
if (ret < 0) {
    //handle error
}

function wc_RsaPrivateDecrypt_ex

int wc_RsaPrivateDecrypt_ex(
    const byte * in,
    word32 inLen,
    byte * out,
    word32 outLen,
    RsaKey * key,
    int type,
    enum wc_HashType hash,
    int mgf,
    byte * label,
    word32 labelSz
)

This function uses RSA to decrypt a message and gives the option of what padding type.

Parameters:

  • in pointer to the buffer for decryption
  • inLen length of the buffer to decrypt
  • out decrypted msg created
  • outLen length of buffer available to hold decrypted msg
  • key initialized RSA key struct
  • type type of padding to use (WC_RSA_OAEP_PAD or WC_RSA_PKCSV15_PAD)
  • hash type of hash to use (choices can be found in hash.h)
  • mgf type of mask generation function to use
  • label an optional label to associate with encrypted message
  • labelSz size of the optional label used

See: none

Return:

  • size On successful decryption, the size of the decrypted message is returned.
  • MEMORY_E Returned if not enough memory on system to malloc a needed array.
  • BAD_FUNC_ARG Returned if a bad argument was passed into the function.

Example

WC_RNG rng;
RsaKey key;
byte in[] = “I use Turing Machines to ask questions”
byte out[256];
byte plain[256];
int ret;
…
ret = wc_RsaPublicEncrypt_ex(in, sizeof(in), out, sizeof(out), &key,
&rng, WC_RSA_OAEP_PAD, WC_HASH_TYPE_SHA, WC_MGF1SHA1, NULL, 0);
if (ret < 0) {
    //handle error
}
…
ret = wc_RsaPrivateDecrypt_ex(out, ret, plain, sizeof(plain), &key,
WC_RSA_OAEP_PAD, WC_HASH_TYPE_SHA, WC_MGF1SHA1, NULL, 0);

if (ret < 0) {
    //handle error
}

function wc_RsaPrivateDecryptInline_ex

int wc_RsaPrivateDecryptInline_ex(
    byte * in,
    word32 inLen,
    byte ** out,
    RsaKey * key,
    int type,
    enum wc_HashType hash,
    int mgf,
    byte * label,
    word32 labelSz
)

This function uses RSA to decrypt a message inline and gives the option of what padding type. The in buffer will contain the decrypted message after being called and the out byte pointer will point to the location in the “in” buffer where the plain text is.

Parameters:

  • in pointer to the buffer for decryption
  • inLen length of the buffer to decrypt
  • out pointer to location of decrypted message in “in” buffer
  • key initialized RSA key struct
  • type type of padding to use (WC_RSA_OAEP_PAD or WC_RSA_PKCSV15_PAD)
  • hash type of hash to use (choices can be found in hash.h)
  • mgf type of mask generation function to use
  • label an optional label to associate with encrypted message
  • labelSz size of the optional label used

See: none

Return:

  • size On successful decryption, the size of the decrypted message is returned.
  • MEMORY_E: Returned if not enough memory on system to malloc a needed array.
  • RSA_PAD_E: Returned if an error in the padding was encountered.
  • BAD_PADDING_E: Returned if an error happened during parsing past padding.
  • BAD_FUNC_ARG: Returned if a bad argument was passed into the function.

Example

WC_RNG rng;
RsaKey key;
byte in[] = “I use Turing Machines to ask questions”
byte out[256];
byte* plain;
int ret;
…
ret = wc_RsaPublicEncrypt_ex(in, sizeof(in), out, sizeof(out), &key,
&rng, WC_RSA_OAEP_PAD, WC_HASH_TYPE_SHA, WC_MGF1SHA1, NULL, 0);

if (ret < 0) {
    //handle error
}
…
ret = wc_RsaPrivateDecryptInline_ex(out, ret, &plain, &key,
WC_RSA_OAEP_PAD, WC_HASH_TYPE_SHA, WC_MGF1SHA1, NULL, 0);

if (ret < 0) {
    //handle error
}

function wc_RsaFlattenPublicKey

int wc_RsaFlattenPublicKey(
    RsaKey * key,
    byte * e,
    word32 * eSz,
    byte * n,
    word32 * nSz
)

Flattens the RsaKey structure into individual elements (e, n) used for the RSA algorithm.

Parameters:

  • key The key to use for verification.
  • e a buffer for the value of e. e is a large positive integer in the RSA modular arithmetic operation.
  • eSz the size of the e buffer.
  • n a buffer for the value of n. n is a large positive integer in the RSA modular arithmetic operation.
  • nSz the size of the n buffer.

See:

Return:

  • 0 Returned if the function executed normally, without error.
  • BAD_FUNC_ARG: Returned if any of the parameters are passed in with a null value.
  • RSA_BUFFER_E: Returned if the e or n buffers passed in are not the correct size.
  • MP_MEM: Returned if an internal function has memory errors.
  • MP_VAL: Returned if an internal function argument is not valid.

Example

Rsa key; // A valid RSA key.
byte e[ buffer sz E.g. 256 ];
byte n[256];
int ret;
word32 eSz = sizeof(e);
word32 nSz = sizeof(n);
...
ret = wc_RsaFlattenPublicKey(&key, e, &eSz, n, &nSz);
if (ret != 0) {
    // Failure case.
}

function wc_RsaKeyToPublicDer

int wc_RsaKeyToPublicDer(
    RsaKey * key,
    byte * output,
    word32 inLen
)

Convert Rsa Public key to DER format. Writes to output, and returns count of bytes written.

Parameters:

  • key The RSA key structure to convert.
  • output Output buffer to hold DER. (if NULL will return length only)
  • inLen Length of buffer.

See:

Return:

  • 0 Success, number of bytes written.

  • BAD_FUNC_ARG Returned if key or output is null.
  • MEMORY_E Returned when an error allocating memory occurs.
  • <0 Error

Example

RsaKey key;

wc_InitRsaKey(&key, NULL);
// Use key

const int BUFFER_SIZE = 1024; // Some adequate size for the buffer
byte output[BUFFER_SIZE];
if (wc_RsaKeyToPublicDer(&key, output, sizeof(output)) != 0) {
    // Handle Error
}

function wc_RsaKeyToPublicDer_ex

int wc_RsaKeyToPublicDer_ex(
    RsaKey * key,
    byte * output,
    word32 inLen,
    int with_header
)

Convert RSA Public key to DER format. Writes to output, and returns count of bytes written. If with_header is 0 then only the ( seq + n + e) is returned in ASN.1 DER format and will exclude the header.

Parameters:

  • key The RSA key structure to convert.
  • output Output buffer to hold DER. (if NULL will return length only)
  • inLen Length of buffer.

See:

Return:

  • 0 Success, number of bytes written.

  • BAD_FUNC_ARG Returned if key or output is null.
  • MEMORY_E Returned when an error allocating memory occurs.
  • <0 Error

Example

RsaKey key;

wc_InitRsaKey(&key, NULL);
// Use key

const int BUFFER_SIZE = 1024; // Some adequate size for the buffer
byte output[BUFFER_SIZE];
if (wc_RsaKeyToPublicDer_ex(&key, output, sizeof(output), 0) != 0) {
    // Handle Error
}

function wc_MakeRsaKey

int wc_MakeRsaKey(
    RsaKey * key,
    int size,
    long e,
    WC_RNG * rng
)

This function generates a RSA private key of length size (in bits) and given exponent (e). It then stores this key in the provided RsaKey structure, so that it may be used for encryption/decryption. A secure number to use for e is 65537. size is required to be greater than RSA_MIN_SIZE and less than RSA_MAX_SIZE. For this function to be available, the option WOLFSSL_KEY_GEN must be enabled at compile time. This can be accomplished with –enable-keygen if using ./configure.

Parameters:

  • key pointer to the RsaKey structure in which to store the generated private key
  • size desired key length, in bits. Required to be greater than RSA_MIN_SIZE and less than RSA_MAX_SIZE
  • e exponent parameter to use for generating the key. A secure choice is 65537
  • rng pointer to an RNG structure to use for random number generation while making the ke

See: none

Return:

  • 0 Returned upon successfully generating a RSA private key
  • BAD_FUNC_ARG Returned if any of the input arguments are NULL, the size parameter falls outside of the necessary bounds, or e is incorrectly chosen
  • RNG_FAILURE_E Returned if there is an error generating a random block using the provided RNG structure
  • MP_INIT_E
  • MP_READ_E May be May be returned if there is an error in the math library used while generating the RSA key returned if there is an error in the math library used while generating the RSA key
  • MP_CMP_E May be returned if there is an error in the math library used while generating the RSA key
  • MP_INVMOD_E May be returned if there is an error in the math library used while generating the RSA key
  • MP_EXPTMOD_E May be returned if there is an error in the math library used while generating the RSA key
  • MP_MOD_E May be returned if there is an error in the math library used while generating the RSA key
  • MP_MUL_E May be returned if there is an error in the math library used while generating the RSA key
  • MP_ADD_E May be returned if there is an error in the math library used while generating the RSA key
  • MP_MULMOD_E May be returned if there is an error in the math library used while generating the RSA key
  • MP_TO_E May be returned if there is an error in the math library used while generating the RSA key
  • MP_MEM May be returned if there is an error in the math library used while generating the RSA key
  • MP_ZERO_E May be returned if there is an error in the math library used while generating the RSA key

Example

RsaKey priv;
WC_RNG rng;
int ret = 0;
long e = 65537; // standard value to use for exponent

wc_InitRsaKey(&priv, NULL); // not using heap hint. No custom memory
wc_InitRng(&rng);
// generate 2048 bit long private key
ret = wc_MakeRsaKey(&priv, 2048, e, &rng);
if( ret != 0 ) {
    // error generating private key
}

function wc_RsaSetNonBlock

int wc_RsaSetNonBlock(
    RsaKey * key,
    RsaNb * nb
)

This function sets the non-blocking RSA context. When a RsaNb context is set it enables fast math based non-blocking exptmod, which splits the RSA function into many smaller operations. Enabled when WC_RSA_NONBLOCK is defined.

Parameters:

  • key The RSA key structure
  • nb The RSA non-blocking structure for this RSA key to use.

See: wc_RsaSetNonBlockTime

Return:

  • 0 Success
  • BAD_FUNC_ARG Returned if key or nb is null.

Example

int ret, count = 0;
RsaKey key;
RsaNb  nb;

wc_InitRsaKey(&key, NULL);

// Enable non-blocking RSA mode - provide context
ret = wc_RsaSetNonBlock(key, &nb);
if (ret != 0)
    return ret;

do {
    ret = wc_RsaSSL_Sign(in, inLen, out, outSz, key, rng);
    count++; // track number of would blocks
    if (ret == FP_WOULDBLOCK) {
        // do "other" work here
    }
} while (ret == FP_WOULDBLOCK);
if (ret < 0) {
    return ret;
}

printf("RSA non-block sign: size %d, %d times\n", ret, count);

function wc_RsaSetNonBlockTime

int wc_RsaSetNonBlockTime(
    RsaKey * key,
    word32 maxBlockUs,
    word32 cpuMHz
)

This function configures the maximum amount of blocking time in microseconds. It uses a pre-computed table (see tfm.c exptModNbInst) along with the CPU speed in megahertz to determine if the next operation can be completed within the maximum blocking time provided. Enabled when WC_RSA_NONBLOCK_TIME is defined.

Parameters:

  • key The RSA key structure.
  • maxBlockUs Maximum time to block microseconds.
  • cpuMHz CPU speed in megahertz.

See: wc_RsaSetNonBlock

Return:

  • 0 Success
  • BAD_FUNC_ARG Returned if key is null or wc_RsaSetNonBlock was not previously called and key->nb is null.

Example

RsaKey key;
RsaNb  nb;

wc_InitRsaKey(&key, NULL);
wc_RsaSetNonBlock(key, &nb);
wc_RsaSetNonBlockTime(&key, 4000, 160); // Block Max = 4 ms, CPU = 160MHz

Updated on 2024-11-22 at 01:12:39 +0000