Ecc C Reference Documentation
Ecc
Current Version: 10.0.0
Elliptical Curve Cryptography class for generating ECDSA keys, computing shared secrets, and creating and verifying ECDSA signatures. Supports the following curves:
- secp256r1 (also known as P-256 and prime256v1)
- secp384r1 (also known as P-384)
- secp521r1 (also known as P-521)
- secp256k1 (This is the curve used for Bitcoin)
- secp192r1
- secp224r1
- brainpoolP160r1
- brainpoolP192r1
- brainpoolP192r1
- brainpoolP224r1
- brainpoolP256r1
- brainpoolP320r1
- brainpoolP384r1
- brainpoolP512r1
Additional curves will be supported in the future.
Create/Dispose
HCkEcc instance = CkEcc_Create(); // ... CkEcc_Dispose(instance);
Creates an instance of the HCkEcc object and returns a handle ("void *" pointer). The handle is passed in the 1st argument for the functions listed on this page.
Objects created by calling CkEcc_Create must be freed by calling this method. A memory leak occurs if a handle is not disposed by calling this function. Also, any handle returned by a Chilkat "C" function must also be freed by the application by calling the appropriate Dispose method, such as CkEcc_Dispose.
Properties
AsnFormat
void CkEcc_putAsnFormat(HCkEcc cHandle, BOOL newVal);
If TRUE, the ECDSA signatures produced by this object will use ASN.1 format. Otherwise the ECDSA signature will be a concatenation of the two raw byte arrays for r and s.
ECDSA signatures have two equal sized parts, r and s. There are two common formats for encoding the signature:
(a) Concatenating the raw byte array of r and s
(b) Encoding both into a structured ASN.1 / DER sequence.
DebugLogFilePath
void CkEcc_putDebugLogFilePath(HCkEcc cHandle, const char *newVal);
const char *CkEcc_debugLogFilePath(HCkEcc cHandle);
If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.
This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:
- a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
- the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
- there is an internal problem (bug) in the Chilkat code that causes the hang.
LastErrorHtml
const char *CkEcc_lastErrorHtml(HCkEcc cHandle);
Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.
topLastErrorText
const char *CkEcc_lastErrorText(HCkEcc cHandle);
Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.
LastErrorXml
const char *CkEcc_lastErrorXml(HCkEcc cHandle);
Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.
topLastMethodSuccess
void CkEcc_putLastMethodSuccess(HCkEcc cHandle, BOOL newVal);
Indicate whether the last method call succeeded or failed. A value of TRUE indicates success, a value of FALSE indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:
- Any method that returns a string.
- Any method returning a Chilkat object, binary bytes, or a date/time.
- Any method returning a standard boolean status value where success = TRUE and failure = FALSE.
- Any method returning an integer where failure is defined by a return value less than zero.
Note: Methods that do not fit the above requirements will always set this property equal to TRUE. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.
topUtf8
void CkEcc_putUtf8(HCkEcc cHandle, BOOL newVal);
When set to TRUE, all "const char *" arguments are interpreted as utf-8 strings. If set to FALSE (the default), then "const char *" arguments are interpreted as ANSI strings. Also, when set to TRUE, and Chilkat method returning a "const char *" is returning the utf-8 representation. If set to FALSE, all "const char *" return values are ANSI strings.
topVerboseLogging
void CkEcc_putVerboseLogging(HCkEcc cHandle, BOOL newVal);
If set to TRUE, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is FALSE. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
topVersion
Methods
GenEccKey
Generates an ECDSA private key. The curveName specifies the curve name which determines the key size. The prng provides a source for generating the random private key.
The following curve names are accepted:
- secp256r1 (also known as P-256 and prime256v1)
- secp384r1 (also known as P-384)
- secp521r1 (also known as P-521)
- secp256k1 (This is the curve used for Bitcoin)
- secp192r1
- secp224r1
- brainpoolP160r1
- brainpoolP192r1
- brainpoolP192r1
- brainpoolP224r1
- brainpoolP256r1
- brainpoolP320r1
- brainpoolP384r1
- brainpoolP512r1
Returns NULL on failure
GenEccKey2
Generates an ECDSA private key using a specified value for K. The curveName specifies the curve name which determines the key size. The encodedK is the encoded value of the private key. The encoding is the encoding used for encodedK, which can be "hex", "base64", "decimal", etc.
Note: This method is typically used for testing -- such as when the same private key is desired to produce results identical from run to run.
The following curve names are accepted:
- secp256r1 (also known as P-256 and prime256v1)
- secp384r1 (also known as P-384)
- secp521r1 (also known as P-521)
- secp256k1 (This is the curve used for Bitcoin)
- secp192r1
- secp224r1
- brainpoolP160r1
- brainpoolP192r1
- brainpoolP192r1
- brainpoolP224r1
- brainpoolP256r1
- brainpoolP320r1
- brainpoolP384r1
- brainpoolP512r1
Returns NULL on failure
SharedSecretENC
const char *CkEcc_sharedSecretENC(HCkEcc cHandle, HCkPrivateKey privKey, HCkPublicKey pubKey, const char *encoding);
Computes a shared secret given a private and public key. For example, Alice and Bob can compute the identical shared secret by doing the following: Alice sends Bob her public key, and Bob calls SharedSecretENC with his private key and Alice's public key. Bob sends Alice his public key, and Alice calls SharedSecretENC with her private key and Bob's public key. Both calls to SharedSecretENC will produce the same result. The resulting bytes are returned in encoded string form (hex, base64, etc) as specified by encoding.
Note: The private and public keys must both be keys on the same ECDSA curve.
Returns TRUE for success, FALSE for failure.
SignBd
const char *CkEcc_signBd(HCkEcc cHandle, HCkBinData bdData, const char *hashAlg, const char *encoding, HCkPrivateKey privKey, HCkPrng prng);
This method is the same as SignHashENC, except the actual data to be signed and the name of the hash algorithm is passed in. The following hash algorithms are supported: sha256, sha384, and sha512.
Returns TRUE for success, FALSE for failure.
SignBdUsingCert
const char *CkEcc_signBdUsingCert(HCkEcc cHandle, HCkBinData bdData, const char *hashAlg, const char *encoding, HCkCert cert);
Same as SignBd, but instead uses the private key of a certificate (assuming the cert's private key is ECDSA).
Returns TRUE for success, FALSE for failure.
topSignHashENC
const char *CkEcc_signHashENC(HCkEcc cHandle, const char *encodedHash, const char *encoding, HCkPrivateKey privkey, HCkPrng prng);
Computes an ECDSA signature on a hash. ECDSA signatures are computed and verified on the hashes of data (such as SHA1, SHA256, etc.). The hash of the data is passed in encodedHash. The encoding, such as "base64", "hex", etc. is passed in encoding. The ECDSA private key is passed in the 3rd argument (privkey). Given that creating an ECDSA signature involves the generation of random numbers, a PRNG is passed in the 4th argument (prng). The signature is returned as an encoded string using the encoding specified by the encoding argument.
Returns TRUE for success, FALSE for failure.
VerifyBd
This method is the same as VerifyHashENC, except the actual data to be verified and the name of the hash algorithm is passed in. The following hash algorithms are supported: sha256, sha384, and sha512.
VerifyHashENC
Verifies an ECDSA signature. ECDSA signatures are computed and verified on the hashes of data (such as SHA1, SHA256, etc.). The hash of the data is passed in encodedHash. The encoded signature is passed in encodedSig. The encoding of both the hash and signature, such as "base64", "hex", etc. is passed in encoding. The ECDSA public key is passed in the last argument (pubkey).
The method returns 1 for a valid signature, 0 for an invalid signature, and -1 for any other failure.