Dsa C Reference Documentation

Dsa

Current Version: 10.0.0

Requires Chilkat Bundle License

The Digital Signature Algorithm (DSA) is a United States Federal Government standard or FIPS for digital signatures. It was proposed by the National Institute of Standards and Technology (NIST) in August 1991 for use in their Digital Signature Standard (DSS).

Create/Dispose

HCkDsa instance = CkDsa_Create();
// ...
CkDsa_Dispose(instance);

HCkDsa CkDsa_Create(void);

Creates an instance of the HCkDsa object and returns a handle ("void *" pointer). The handle is passed in the 1st argument for the functions listed on this page.

void CkDsa_Dispose(HCkDsa handle);

Objects created by calling CkDsa_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 CkDsa_Dispose.

Properties

DebugLogFilePath

void CkDsa_getDebugLogFilePath(HCkDsa cHandle, HCkString retval);
void CkDsa_putDebugLogFilePath(HCkDsa cHandle, const char *newVal);
const char *CkDsa_debugLogFilePath(HCkDsa 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.

More Information and Examples

Example showing how to use DebugLogFilePath.

GroupSize

int CkDsa_getGroupSize(HCkDsa cHandle);
void CkDsa_putGroupSize(HCkDsa cHandle, int newVal);

The group size (in bits) to be used in DSA key generation. The default value is 160 and corresponds to the fact that SHA-1 is used in signature generation. This property setting should not be changed. It exists for future expansion when additional underlying hash algorithms are supported.

Hash

void CkDsa_getHash(HCkDsa cHandle, HCkByteData retval);
void CkDsa_putHash(HCkDsa cHandle, HCkByteData newVal);

The hash to be signed or verified via the SignHash and Verify methods. In both cases, the Hash should be set prior to calling SignHash or Verify. This property may also be set via the SetEncodedHash method.

HexG

void CkDsa_getHexG(HCkDsa cHandle, HCkString retval);
const char *CkDsa_hexG(HCkDsa cHandle);

The "G" part of a public or private DSA key returned as a hex-encoded SSH1-format bignum. The "G" is the generator. DSA key params consist of G, P, and Q.

HexP

void CkDsa_getHexP(HCkDsa cHandle, HCkString retval);
const char *CkDsa_hexP(HCkDsa cHandle);

The "P" part of a public or private DSA key returned as a hex-encoded SSH1-format bignum. The "P" is a large prime. DSA key params consist of G, P, and Q.

HexQ

void CkDsa_getHexQ(HCkDsa cHandle, HCkString retval);
const char *CkDsa_hexQ(HCkDsa cHandle);

The "Q" part of a public or private DSA key returned as a hex-encoded SSH1-format bignum. DSA key params consist of G, P, and Q.

HexX

void CkDsa_getHexX(HCkDsa cHandle, HCkString retval);
const char *CkDsa_hexX(HCkDsa cHandle);

The "X" part of a DSA private key returned as a hex-encoded SSH1-format bignum.

HexY

void CkDsa_getHexY(HCkDsa cHandle, HCkString retval);
const char *CkDsa_hexY(HCkDsa cHandle);

The "Y" part of a DSA public key returned as a hex-encoded SSH1-format bignum. (The "Y" value is also accessible w/ a private key, but the "X" value is not available in a DSA public key.)

LastErrorHtml

void CkDsa_getLastErrorHtml(HCkDsa cHandle, HCkString retval);
const char *CkDsa_lastErrorHtml(HCkDsa 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.

LastErrorText

void CkDsa_getLastErrorText(HCkDsa cHandle, HCkString retval);
const char *CkDsa_lastErrorText(HCkDsa 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.

More Information and Examples

Concept of LastErrorText LastErrorText Standard Information

LastErrorXml

void CkDsa_getLastErrorXml(HCkDsa cHandle, HCkString retval);
const char *CkDsa_lastErrorXml(HCkDsa 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.

LastMethodSuccess

BOOL CkDsa_getLastMethodSuccess(HCkDsa cHandle);
void CkDsa_putLastMethodSuccess(HCkDsa 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.

Signature

void CkDsa_getSignature(HCkDsa cHandle, HCkByteData retval);
void CkDsa_putSignature(HCkDsa cHandle, HCkByteData newVal);

The signature created by calling SignHash. If verifying a signature, this may be set prior to calling the Verify method.

UncommonOptions

void CkDsa_getUncommonOptions(HCkDsa cHandle, HCkString retval);
void CkDsa_putUncommonOptions(HCkDsa cHandle, const char *newVal);
const char *CkDsa_uncommonOptions(HCkDsa cHandle);

Introduced in version 9.5.0.90

This is a catch-all property to be used for uncommon needs. This property defaults to the empty string and should typically remain empty.

Utf8

BOOL CkDsa_getUtf8(HCkDsa cHandle);
void CkDsa_putUtf8(HCkDsa 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.

VerboseLogging

BOOL CkDsa_getVerboseLogging(HCkDsa cHandle);
void CkDsa_putVerboseLogging(HCkDsa 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.

Version

void CkDsa_getVersion(HCkDsa cHandle, HCkString retval);
const char *CkDsa_version(HCkDsa cHandle);

Version of the component/library, such as "9.5.0.94"

More Information and Examples

How to get the Chilkat version at runtime.

Methods

FromDer

BOOL CkDsa_FromDer(HCkDsa cHandle, HCkByteData derData);

Loads a DSA private key from in-memory DSA DER-encoded bytes.

Returns TRUE for success, FALSE for failure.

FromDerFile

BOOL CkDsa_FromDerFile(HCkDsa cHandle, const char *path);

Loads a DSA private key from a DER-encoded file.

Returns TRUE for success, FALSE for failure.

More Information and Examples

Convert DSA DER Private Key to PEM

FromEncryptedPem

BOOL CkDsa_FromEncryptedPem(HCkDsa cHandle, const char *password, const char *pemData);

Loads a DSA private key from an in-memory encrypted PEM-formatted string. If the PEM passed to this method is unencrypted, the password is ignored and the PEM is simply loaded.

Returns TRUE for success, FALSE for failure.

FromPem

BOOL CkDsa_FromPem(HCkDsa cHandle, const char *pemData);

Loads a DSA private key from an in-memory unencrypted PEM-formatted string.

Returns TRUE for success, FALSE for failure.

More Information and Examples

DSA Signature Create and Verify

FromPublicDer

BOOL CkDsa_FromPublicDer(HCkDsa cHandle, HCkByteData derData);

Loads a DSA public key from an in-memory DER-encoded byte array.

Returns TRUE for success, FALSE for failure.

FromPublicDerFile

BOOL CkDsa_FromPublicDerFile(HCkDsa cHandle, const char *path);

Loads a DSA public key from a DER-encoded file.

Returns TRUE for success, FALSE for failure.

FromPublicPem

BOOL CkDsa_FromPublicPem(HCkDsa cHandle, const char *pemData);

Loads a DSA public-key from an in-memory PEM string.

Returns TRUE for success, FALSE for failure.

FromXml

BOOL CkDsa_FromXml(HCkDsa cHandle, const char *xmlKey);

Loads a DSA public or private key from an in-memory XML string.

Returns TRUE for success, FALSE for failure.

GenKey

BOOL CkDsa_GenKey(HCkDsa cHandle, int numBits);

Generates a new DSA key that is numBits bits in length. The numBits should be at least 1024 bits and a multiple of 64. Typical values are 1024 and 2048. The newly generated key may be exported by calling one of the To* methods.

Returns TRUE for success, FALSE for failure.

More Information and Examples

DSA Generate Key

GenKey2

BOOL CkDsa_GenKey2(HCkDsa cHandle, int keyLenBits, int modLenBits);

Introduced in version 9.5.0.90

Generates a new DSA key that is keyLenBits bits in length with a modulus of size modLenBits bits. The keyLenBits should be at least 1024 bits and a multiple of 64. FIPS 186-4 specifies the key length (bits) and modulus size (bits) to have one of the values: (1024, 160), (2048, 224), (2048, 256), or (3072, 256).

Returns TRUE for success, FALSE for failure.

GenKeyFromParamsDer

BOOL CkDsa_GenKeyFromParamsDer(HCkDsa cHandle, HCkByteData derBytes);

Generates a new DSA key from in-memory DER parameters created by OpenSSL. The newly generated key may be exported by calling one of the To* methods.

Returns TRUE for success, FALSE for failure.

GenKeyFromParamsDerFile

BOOL CkDsa_GenKeyFromParamsDerFile(HCkDsa cHandle, const char *path);

Generates a new DSA key from a DER-format parameters file created by OpenSSL. An example of using OpenSSL to generate DSA parameters in DER format is:

openssl dsaparam -outform DER 1024 < seedData.xml > dsaparam.der

The newly generated key may be exported by calling one of the To* methods.

Returns TRUE for success, FALSE for failure.

More Information and Examples

Generate new DSA Key from OpenSSL Parameters File

GenKeyFromParamsPem

BOOL CkDsa_GenKeyFromParamsPem(HCkDsa cHandle, const char *pem);

Generates a new DSA key from parameters (PEM formatted string) created by OpenSSL. The newly generated key may be exported by calling one of the To* methods.

Returns TRUE for success, FALSE for failure.

GenKeyFromParamsPemFile

BOOL CkDsa_GenKeyFromParamsPemFile(HCkDsa cHandle, const char *path);

Generates a new DSA key from a PEM parameters file created by OpenSSL. The newly generated key may be exported by calling one of the To* methods.

OpenSSL provides the ability to generate DSA key parameters. For example:

openssl dsaparam 1024 < seedData.txt > dsaparam.pem

Here is a sample DSA parameters PEM:

-----BEGIN DSA PARAMETERS-----
MIIBHgKBgQCXIAx4XzLVZ5ZqOFzdsYWVyH/6E/mVPw4TgMZS6Wxajnbdn1/CUBzE
RWTUp8SguTSDpjC1Q/nyno0G6Q96VoW+PUXv8qUph8vbSaEdsjYO/8jSfzkGfvsa
cucr1ythfNyk63aZAKzxeutOmsVe77l6pZI96ROjWF5iizuUB4WgmwIVANxM70wH
8iPPYVzPZqtXCB66I2SnAoGAIbW2VYRjRdoA7trJgmnfWakghKwV1WyaYrotqeDE
07/dipp0cNuY0IAJgSmqLHlAkNa2ZNI/c1mNxcwhYzZrnn8CXIqrYmtI33w0PYCx
KHPqj7puhddFwYS/rFiyWAN0jtCMHlfCVzFGbSzach5QQraPV9YApJXy+ORJ8VPU
/zo=
-----END DSA PARAMETERS-----

Returns TRUE for success, FALSE for failure.

GenKeyFromPQG

BOOL CkDsa_GenKeyFromPQG(HCkDsa cHandle, const char *pHex, const char *qHex, const char *gHex);

Introduced in version 9.5.0.90

Generates a new DSA key from pre-chosen P, Q, and G params.

Returns TRUE for success, FALSE for failure.

GetEncodedHash

BOOL CkDsa_GetEncodedHash(HCkDsa cHandle, const char *encoding, HCkString outStr);
const char *CkDsa_getEncodedHash(HCkDsa cHandle, const char *encoding);

Returns the bytes of the Hash property as a hex or base64 encoded string. The encoding should be set to either "hex" or "base64".

Returns TRUE for success, FALSE for failure.

GetEncodedSignature

BOOL CkDsa_GetEncodedSignature(HCkDsa cHandle, const char *encoding, HCkString outStr);
const char *CkDsa_getEncodedSignature(HCkDsa cHandle, const char *encoding);

Returns the bytes of the Signature property as a hex or base64 encoded string. The encoding should be set to either "hex" or "base64". The Signature property is set when SignHash is called.

Returns TRUE for success, FALSE for failure.

LoadText

BOOL CkDsa_LoadText(HCkDsa cHandle, const char *path, HCkString outStr);
const char *CkDsa_loadText(HCkDsa cHandle, const char *path);

Convenience method to load the entire contents of a text file into a string. It is assumed that the text contains ANSI encoded character data.

Returns TRUE for success, FALSE for failure.

SaveText

BOOL CkDsa_SaveText(HCkDsa cHandle, const char *strToSave, const char *path);

Convenience method to save a string to a text file. The text is saved using the ANSI character encoding.

Returns TRUE for success, FALSE for failure.

SetEncodedHash

BOOL CkDsa_SetEncodedHash(HCkDsa cHandle, const char *encoding, const char *encodedHash);

Provides a way to set the Hash property by passing an encoded string. The encoding can be "hex" or "base64". The encodedHash contains the encoded bytes of the hash that will be signed or verified via the SignHash and Verify methods.

Returns TRUE for success, FALSE for failure.

SetEncodedSignature

BOOL CkDsa_SetEncodedSignature(HCkDsa cHandle, const char *encoding, const char *encodedSig);

Sets the bytes of the Signature property. (The signature must be specified prior to calling the Verify method.) This method allows for the signature to be set via a hex or base64 encoded string. The encoding should be set to either "hex" or "base64".

Returns TRUE for success, FALSE for failure.

SetEncodedSignatureRS

BOOL CkDsa_SetEncodedSignatureRS(HCkDsa cHandle, const char *encoding, const char *encodedR, const char *encodedS);

Sets the bytes of the Signature property by providing the R and S values in encoded form. (The signature must be specified prior to calling the Verify method.) The R and S values may be set via a hex or base64 encoded string. The encoding should be set to either "hex" or "base64".

Returns TRUE for success, FALSE for failure.

SetKeyExplicit

BOOL CkDsa_SetKeyExplicit(HCkDsa cHandle, int groupSizeInBytes, const char *pHex, const char *qHex, const char *gHex, const char *xHex);

Sets the DSA object's private key from explicitly provided pHex, qHex, gHex, and xHex values. The groupSizeInBytes specifies the group size (in bytes). It is typically equal to 20, which is the length of the underlying hash function (SHA-1) for signing. The pHex, qHex, gHex, and xHex values are hex-encoded SSH1-format bignums.

Returns TRUE for success, FALSE for failure.

SetPubKeyExplicit

BOOL CkDsa_SetPubKeyExplicit(HCkDsa cHandle, int groupSizeInBytes, const char *pHex, const char *qHex, const char *gHex, const char *yHex);

Sets the DSA object's private key from explicitly provided pHex, qHex, gHex, and yHex values. The groupSizeInBytes specifies the group size (in bytes). It is typically equal to 20, which is the length of the underlying hash function (SHA-1) for signing. The pHex, qHex, gHex, and yHex values are hex-encoded SSH1-format bignums.

Returns TRUE for success, FALSE for failure.

SignHash

BOOL CkDsa_SignHash(HCkDsa cHandle);

Signs a hash using the digital signature algorithm. Before calling this method, set the hash to be signed by either calling SetEncodedHash or by setting the Hash property. If SignHash returns TRUE, the signature may be retrieved by either calling GetEncodedHash, or by accessing the Signature property.

Returns TRUE for success, FALSE for failure.

More Information and Examples

DSA Signature Create and Verify

ToDer

BOOL CkDsa_ToDer(HCkDsa cHandle, HCkByteData outBytes);

Writes the DSA private key to a DER-encoded byte array.

Returns TRUE for success, FALSE for failure.

ToDerFile

BOOL CkDsa_ToDerFile(HCkDsa cHandle, const char *path);

Writes the DSA private key to a DER-format file.

Returns TRUE for success, FALSE for failure.

More Information and Examples

DSA Generate Key

ToEncryptedPem

BOOL CkDsa_ToEncryptedPem(HCkDsa cHandle, const char *password, HCkString outStr);
const char *CkDsa_toEncryptedPem(HCkDsa cHandle, const char *password);

Writes the DSA private key to an in-memory encrypted PEM string.

Returns TRUE for success, FALSE for failure.

More Information and Examples

DSA Generate Key Convert DSA DER Private Key to PEM

ToPem

BOOL CkDsa_ToPem(HCkDsa cHandle, HCkString outStr);
const char *CkDsa_toPem(HCkDsa cHandle);

Writes the DSA private key to an in-memory PEM string.

Returns TRUE for success, FALSE for failure.

More Information and Examples

Convert DSA DER Private Key to PEM

ToPublicDer

BOOL CkDsa_ToPublicDer(HCkDsa cHandle, HCkByteData outBytes);

Writes the DSA public key to a DER-encoded byte array.

Returns TRUE for success, FALSE for failure.

ToPublicDerFile

BOOL CkDsa_ToPublicDerFile(HCkDsa cHandle, const char *path);

Writes the DSA public key to a DER-format file.

Returns TRUE for success, FALSE for failure.

More Information and Examples

DSA Generate Key

ToPublicPem

BOOL CkDsa_ToPublicPem(HCkDsa cHandle, HCkString outStr);
const char *CkDsa_toPublicPem(HCkDsa cHandle);

Writes the DSA public key to an in-memory PEM string.

Returns TRUE for success, FALSE for failure.

More Information and Examples

DSA Generate Key

ToXml

BOOL CkDsa_ToXml(HCkDsa cHandle, BOOL bPublicOnly, HCkString outStr);
const char *CkDsa_toXml(HCkDsa cHandle, BOOL bPublicOnly);

Writes the DSA private or public key to an in-memory XML string. The bPublicOnly determines whether the public or private key is written.

Returns TRUE for success, FALSE for failure.

More Information and Examples

DSA Get Key as XML

Verify

BOOL CkDsa_Verify(HCkDsa cHandle);

Verifies a DSA signature. The Hash and Signature properties must be set prior to calling this method. (These properties may also be set via the SetEncodedHash and SetEncodedSignature methods.)

Returns TRUE for success, FALSE for failure.

More Information and Examples

DSA Signature Create and Verify DSA R,S Signature Values

VerifyKey

BOOL CkDsa_VerifyKey(HCkDsa cHandle);

Verifies that the public or private key contained in the calling Dsa object is valid. Returns TRUE if valid, otherwise returns FALSE.

More Information and Examples

DSA Signature Create and Verify