ECCPSignDSA
ECCPSignDSA
Computes a digital signature over a message digest.
Syntax
IppStatus ippsECCPSignDSA(const IppsBigNumState*
pMsgDigest
, const IppsBigNumState*
pPrivate
, IppsBigNumState*
pSignX
, IppsBigNumState*
pSignY
, IppsECCPState*
pECC
);
Include Files
ippcp.h
Parameters
- pMsgDigest
- Pointer to the message digestmsgto be digitally signed, that is, to be ecrypted with a private key.
- pPrivate
- Pointer to the signer's regular private key.
- pSignX
- Pointer to the integerrof the digital signature.
- pSignY
- Pointer to the integersof the digital signature.
- pECC
- Pointer to the context of the elliptic cryptosystem.
Description
A message digest is a fixed size number derived from the original message with an applied hash function over the binary code of the message. The signer's private key and the message digest are used to create a signature.
A digital signature over a message consists of a pair of large numbers
r
and s
which the given function computes. The scheme used for computing a digital signature is the ECDSA scheme, an elliptic curve analogue of the DSA scheme. ECDSA assumes that the following keys are hitherto set by a message signer:
- regPrivKey
- Regular private key.
- ephPrivKey
- Ephemeral private key.
- ephPubKey
- Ephemeral public key.
For security reasons, each signature must be generated with the unique ephemeral private key. Because of this, the function clears (sets to zero) the input ephemeral key before return. To generate and set up the keys before sign generation, call the
ECCPGenKeyPair
and ECCPSetKeyPair
functions.The elliptic curve domain parameters must be hitherto defined by one of the functions:
ECCPSet
or ECCPSetStd
.For more information on digital signatures, please refer to the [ANSI] standard.
Return Values
- ippStsNoErr
- Indicates no error. Any other value indicates an error or warning.
- ippStsNullPtrErr
- Indicates an error condition if any of the specified pointers isNULL.
- ippStsContextMatchErr
- Indicates an error condition if one of the contexts pointed bypMsgDigest,pSignX,pSignY, orECCis not valid.
- ippStsMessageErr
- Indicates an error condition if the value ofmsgpointed bypMsgDigestis negative, or the bit length is greater than the bit length ofn, wherenis the order of the elliptic curve base pointG.
- ippStsRangeErr
- Indicates an error condition if one of the parameters pointed bypSignXorpSignYhas a memory size smaller than the ordernof the elliptic curve base pointG.
- ippStsEphemeralKeyErr
- Indicates an error condition if the values of the ephemeral keysephPrivKeyandephPubKeyare not valid. (Eitherr =0 ors =0 is received as a result of the digital signature calculation).
- ippStsInvalidPrivateKey
- Indicates an error condition if the private key value does not belong to the [0, n-1] range, wherenis the order of the elliptic curve base pointG.