/****************************************************************************
*																			*
*						cryptlib DSA Encryption Routines					*
*						Copyright Peter Gutmann 1995-2005					*
*																			*
****************************************************************************/

#define PKC_CONTEXT		/* Indicate that we're working with PKC contexts */
#if defined( INC_ALL )
  #include "crypt.h"
  #include "context.h"
#else
  #include "crypt.h"
  #include "context/context.h"
#endif /* Compiler-specific includes */

/****************************************************************************
*																			*
*						Predefined DSA p, q, and g Parameters				*
*																			*
****************************************************************************/

/* We never use shared DSA parameters because they allow forgery of
   signatures on certificates.  This works as follows: Suppose that the
   certificate contains a copy of the certificate signer's DSA parameters,
   and the verifier of the certificate has a copy of the signer's public key
   but not the signer's DSA parameters (which are shared with other keys).
   If the verifier uses the DSA parameters from the certificate along with
   the signer's public key to verify the signature on the certificate, then
   an attacker can create bogus certificates by choosing a random u and
   finding its inverse v modulo q (uv is congruent to 1 modulo q).  Then
   take the certificate signer's public key g^x and compute g' = (g^x)^u.
   Then g'^v = g^x.  Using the DSA parameters p, q, g', the signer's public
   key corresponds to the private key v, which the attacker knows.  The
   attacker can then create a bogus certificate, put parameters (p, q, g')
   in it, and sign it with the DSA private key v to create an apparently
   valid certificate.  This works with the DSA OID that makes p, q, and g
   unauthenticated public parameters and y the public key, but not the one
   that makes p, q, g, and y the public key */

/****************************************************************************
*																			*
*								Algorithm Self-test							*
*																			*
****************************************************************************/

/* Since we're doing the self-test using the FIPS 186 values we use the 
   following fixed k and hash values rather than a randomly-generated 
   value */

static const BYTE FAR_BSS shaM[] = {
	0xA9, 0x99, 0x3E, 0x36, 0x47, 0x06, 0x81, 0x6A,
	0xBA, 0x3E, 0x25, 0x71, 0x78, 0x50, 0xC2, 0x6C,
	0x9C, 0xD0, 0xD8, 0x9D
	};

static const BYTE FAR_BSS kVal[] = {
	0x35, 0x8D, 0xAD, 0x57, 0x14, 0x62, 0x71, 0x0F,
	0x50, 0xE2, 0x54, 0xCF, 0x1A, 0x37, 0x6B, 0x2B,
	0xDE, 0xAA, 0xDF, 0xBF
	};

/* Perform a pairwise consistency test on a public/private key pair */

static BOOLEAN pairwiseConsistencyTest( CONTEXT_INFO *contextInfoPtr )
	{
	const CAPABILITY_INFO *capabilityInfoPtr = contextInfoPtr->capabilityInfo;
	DLP_PARAMS dlpParams;
	BYTE buffer[ 128 + 8 ];
	int sigSize, status;

	/* Generate a signature with the private key */
	setDLPParams( &dlpParams, shaM, 20, buffer, 128 );
	dlpParams.inLen2 = -999;
	status = capabilityInfoPtr->signFunction( contextInfoPtr,
						( BYTE * ) &dlpParams, sizeof( DLP_PARAMS ) );
	if( cryptStatusError( status ) )
		return( FALSE );

	/* Verify the signature with the public key */
	sigSize = dlpParams.outLen;
	setDLPParams( &dlpParams, shaM, 20, NULL, 0 );
	dlpParams.inParam2 = buffer;
	dlpParams.inLen2 = sigSize;
	status = capabilityInfoPtr->sigCheckFunction( contextInfoPtr,
						( BYTE * ) &dlpParams, sizeof( DLP_PARAMS ) );
	return( cryptStatusOK( status ) ? TRUE : FALSE );
	}

#ifndef CONFIG_NO_SELFTEST

/* Test the DSA implementation using the sample key and hash from FIPS 186
   (we actually use a generated 1024-bit key because the FIPS 186 key at
   512 bits is too short to load).  Because a lot of the high-level 
   encryption routines don't exist yet, we cheat a bit and set up a dummy 
   encryption context with just enough information for the following code to 
   work */

typedef struct {
	const int pLen; const BYTE p[ 128 ];
	const int qLen; const BYTE q[ 20 ];
	const int gLen; const BYTE g[ 128 ];
	const int xLen; const BYTE x[ 20 ];
	const int yLen; const BYTE y[ 128 ];
	} DLP_KEY;

#if 0	/* FIPS 186 test key is too small to be loaded */

static const DLP_PRIVKEY FAR_BSS dlpTestKey = {
	/* p */
	64,
	{ 0x8D, 0xF2, 0xA4, 0x94, 0x49, 0x22, 0x76, 0xAA,
	  0x3D, 0x25, 0x75, 0x9B, 0xB0, 0x68, 0x69, 0xCB,
	  0xEA, 0xC0, 0xD8, 0x3A, 0xFB, 0x8D, 0x0C, 0xF7,
	  0xCB, 0xB8, 0x32, 0x4F, 0x0D, 0x78, 0x82, 0xE5,
	  0xD0, 0x76, 0x2F, 0xC5, 0xB7, 0x21, 0x0E, 0xAF,
	  0xC2, 0xE9, 0xAD, 0xAC, 0x32, 0xAB, 0x7A, 0xAC,
	  0x49, 0x69, 0x3D, 0xFB, 0xF8, 0x37, 0x24, 0xC2,
	  0xEC, 0x07, 0x36, 0xEE, 0x31, 0xC8, 0x02, 0x91 },
	/* q */
	20,
	{ 0xC7, 0x73, 0x21, 0x8C, 0x73, 0x7E, 0xC8, 0xEE,
	  0x99, 0x3B, 0x4F, 0x2D, 0xED, 0x30, 0xF4, 0x8E,
	  0xDA, 0xCE, 0x91, 0x5F },
	/* g */
	64,
	{ 0x62, 0x6D, 0x02, 0x78, 0x39, 0xEA, 0x0A, 0x13,
	  0x41, 0x31, 0x63, 0xA5, 0x5B, 0x4C, 0xB5, 0x00,
	  0x29, 0x9D, 0x55, 0x22, 0x95, 0x6C, 0xEF, 0xCB,
	  0x3B, 0xFF, 0x10, 0xF3, 0x99, 0xCE, 0x2C, 0x2E,
	  0x71, 0xCB, 0x9D, 0xE5, 0xFA, 0x24, 0xBA, 0xBF,
	  0x58, 0xE5, 0xB7, 0x95, 0x21, 0x92, 0x5C, 0x9C,
	  0xC4, 0x2E, 0x9F, 0x6F, 0x46, 0x4B, 0x08, 0x8C,
	  0xC5, 0x72, 0xAF, 0x53, 0xE6, 0xD7, 0x88, 0x02 },
	/* x */
	20,
	{ 0x20, 0x70, 0xB3, 0x22, 0x3D, 0xBA, 0x37, 0x2F,
	  0xDE, 0x1C, 0x0F, 0xFC, 0x7B, 0x2E, 0x3B, 0x49,
	  0x8B, 0x26, 0x06, 0x14 },
	/* y */
	64,
	{ 0x19, 0x13, 0x18, 0x71, 0xD7, 0x5B, 0x16, 0x12,
	  0xA8, 0x19, 0xF2, 0x9D, 0x78, 0xD1, 0xB0, 0xD7,
	  0x34, 0x6F, 0x7A, 0xA7, 0x7B, 0xB6, 0x2A, 0x85,
	  0x9B, 0xFD, 0x6C, 0x56, 0x75, 0xDA, 0x9D, 0x21,
	  0x2D, 0x3A, 0x36, 0xEF, 0x16, 0x72, 0xEF, 0x66,
	  0x0B, 0x8C, 0x7C, 0x25, 0x5C, 0xC0, 0xEC, 0x74,
	  0x85, 0x8F, 0xBA, 0x33, 0xF4, 0x4C, 0x06, 0x69,
	  0x96, 0x30, 0xA7, 0x6B, 0x03, 0x0E, 0xE3, 0x33 }
	};
#endif /* 0 */

static const DLP_KEY FAR_BSS dlpTestKey = {
	/* p */
	128,
	{ 0x04, 0x4C, 0xDD, 0x5D, 0xB6, 0xED, 0x23, 0xAE, 
	  0xB2, 0xA7, 0x59, 0xE6, 0xF8, 0x3D, 0xA6, 0x27, 
	  0x85, 0xF2, 0xFE, 0xE2, 0xE8, 0xF3, 0xDA, 0xA3, 
	  0x7B, 0xD6, 0x48, 0xD4, 0x44, 0xCA, 0x6E, 0x10, 
	  0x97, 0x6C, 0x1D, 0x6C, 0x39, 0xA7, 0x0C, 0x88, 
	  0x8E, 0x1F, 0xDD, 0xF7, 0x59, 0x69, 0xDA, 0x36, 
	  0xDD, 0xB8, 0x3E, 0x1A, 0xD2, 0x91, 0x3E, 0x30, 
	  0xB1, 0xB5, 0xC2, 0xBC, 0xA9, 0xA3, 0xA5, 0xDE, 
	  0xC7, 0xCF, 0x51, 0x2C, 0x1B, 0x89, 0xD0, 0x71, 
	  0xE3, 0x71, 0xBB, 0x50, 0x86, 0x26, 0x32, 0x9F, 
	  0xF5, 0x4A, 0x9C, 0xB1, 0x78, 0x7B, 0x47, 0x1F, 
	  0x19, 0xC7, 0x26, 0x22, 0x15, 0x62, 0x71, 0xAB, 
	  0xD7, 0x25, 0xA5, 0xE4, 0x68, 0x71, 0x93, 0x5D, 
	  0x1F, 0x29, 0x01, 0x05, 0x9C, 0x57, 0x3A, 0x09, 
	  0xB0, 0xB8, 0xE4, 0xD2, 0x37, 0x90, 0x36, 0x2F, 
	  0xBF, 0x1E, 0x74, 0xB4, 0x6B, 0xE4, 0x66, 0x07 }, 

	/* q */
	20,
	{ 0xFD, 0xD9, 0xC8, 0x5F, 0x73, 0x62, 0xC9, 0x79, 
	  0xEF, 0xD5, 0x09, 0x07, 0x02, 0xE7, 0xF2, 0x90, 
	  0x97, 0x13, 0x26, 0x1D }, 

	/* g */
	128,
	{ 0x02, 0x4E, 0xDD, 0x0D, 0x7F, 0x4D, 0xB1, 0x42, 
	  0x01, 0x50, 0xE7, 0x9A, 0x65, 0x73, 0x8B, 0x31, 
	  0x24, 0x6B, 0xC6, 0x74, 0xA7, 0x68, 0x26, 0x11, 
	  0x06, 0x3C, 0x96, 0xA9, 0xA6, 0x23, 0x12, 0x79, 
	  0xC4, 0xEE, 0x21, 0x88, 0xDD, 0xE3, 0xF0, 0x37, 
	  0xCE, 0x3E, 0x54, 0x53, 0x57, 0x03, 0x30, 0xE4, 
	  0xD3, 0xAB, 0x39, 0x4E, 0x39, 0xDC, 0xA2, 0x88, 
	  0x82, 0xF6, 0xE8, 0xBA, 0xAC, 0xF5, 0x7D, 0x2F, 
	  0x23, 0x9A, 0x09, 0x94, 0xB2, 0x89, 0xA2, 0xC9, 
	  0x7C, 0xBE, 0x4D, 0x48, 0x0E, 0x59, 0x51, 0xB8, 
	  0x7D, 0x99, 0x88, 0x79, 0xA8, 0x13, 0x0E, 0x12, 
	  0x56, 0x9D, 0x4B, 0x2E, 0xE0, 0xE1, 0x37, 0x78, 
	  0x6F, 0xCC, 0x4D, 0x97, 0xA9, 0x02, 0x0E, 0xD2, 
	  0x43, 0x83, 0xEC, 0x4F, 0xC2, 0x70, 0xEF, 0x16, 
	  0xDE, 0xBF, 0xBA, 0xD1, 0x6C, 0x8A, 0x36, 0xEE, 
	  0x42, 0x41, 0xE9, 0xE7, 0x66, 0xAE, 0x46, 0x3B }, 

	/* x */
	20,
	{ 0xD9, 0x41, 0x29, 0xF7, 0x40, 0x32, 0x09, 0x71, 
	  0xB8, 0xE2, 0xB8, 0xCB, 0x74, 0x46, 0x0B, 0xD4, 
	  0xF2, 0xAB, 0x54, 0xA1 }, 

	/* y */
	128,
	{ 0x01, 0x7E, 0x16, 0x5B, 0x65, 0x51, 0x0A, 0xDA, 
	  0x82, 0x1A, 0xD9, 0xF4, 0x1E, 0x66, 0x6D, 0x7D, 
	  0x23, 0xA6, 0x28, 0x2F, 0xE6, 0xC2, 0x03, 0x8E, 
	  0x8C, 0xAB, 0xC2, 0x08, 0x87, 0xC9, 0xE8, 0x51, 
	  0x0A, 0x37, 0x1E, 0xD4, 0x41, 0x7F, 0xA2, 0xC5, 
	  0x48, 0x26, 0xB7, 0xF6, 0xC2, 0x6F, 0xB2, 0xF8, 
	  0xF9, 0x43, 0x43, 0xF9, 0xDA, 0xAB, 0xA2, 0x59, 
	  0x27, 0xBA, 0xC9, 0x1C, 0x8C, 0xAB, 0xC4, 0x90, 
	  0x27, 0xE1, 0x10, 0x39, 0x6F, 0xD2, 0xCD, 0x7C, 
	  0xD1, 0x0B, 0xFA, 0x28, 0xD2, 0x7A, 0x7B, 0x52, 
	  0x8A, 0xA0, 0x5A, 0x0F, 0x10, 0xF7, 0xBA, 0xFD, 
	  0x33, 0x0C, 0x3C, 0xCE, 0xE5, 0xF2, 0xF6, 0x92, 
	  0xED, 0x04, 0xBF, 0xD3, 0xF8, 0x3D, 0x39, 0xCC, 
	  0xAA, 0xCC, 0x0B, 0xB2, 0x6B, 0xD8, 0xB2, 0x8A, 
	  0x5C, 0xCE, 0xDA, 0xF9, 0xE1, 0xA7, 0x23, 0x50, 
	  0xDC, 0xCE, 0xA4, 0xD5, 0xA5, 0x4F, 0x08, 0x0F }
	};

static int selfTest( void )
	{
	CONTEXT_INFO contextInfo;
	PKC_INFO contextData, *pkcInfo = &contextData;
	int status;

	/* Initialise the key components */
	status = staticInitContext( &contextInfo, CONTEXT_PKC, 
								getDSACapability(), &contextData, 
								sizeof( PKC_INFO ), NULL );
	if( cryptStatusError( status ) )
		return( CRYPT_ERROR_FAILED );
	status = importBignum( &pkcInfo->dlpParam_p, dlpTestKey.p, 
						   dlpTestKey.pLen, DLPPARAM_MIN_P, 
						   DLPPARAM_MAX_P, NULL, SHORTKEY_CHECK_PKC );
	if( cryptStatusOK( status ) ) 
		status = importBignum( &pkcInfo->dlpParam_q, dlpTestKey.q, 
							   dlpTestKey.qLen, DLPPARAM_MIN_Q, 
							   DLPPARAM_MAX_Q, &pkcInfo->dlpParam_p, 
							   SHORTKEY_CHECK_NONE );
	if( cryptStatusOK( status ) ) 
		status = importBignum( &pkcInfo->dlpParam_g, dlpTestKey.g, 
							   dlpTestKey.gLen, DLPPARAM_MIN_G, 
							   DLPPARAM_MAX_G, &pkcInfo->dlpParam_p,
							   SHORTKEY_CHECK_NONE );
	if( cryptStatusOK( status ) ) 
		status = importBignum( &pkcInfo->dlpParam_y, dlpTestKey.y, 
							   dlpTestKey.yLen, DLPPARAM_MIN_Y, 
							   DLPPARAM_MAX_Y, &pkcInfo->dlpParam_p,
							   SHORTKEY_CHECK_NONE );
	if( cryptStatusOK( status ) ) 
		status = importBignum( &pkcInfo->dlpParam_x, dlpTestKey.x, 
							   dlpTestKey.xLen, DLPPARAM_MIN_X, 
							   DLPPARAM_MAX_X, &pkcInfo->dlpParam_p, 
							   SHORTKEY_CHECK_NONE );
	if( cryptStatusError( status ) ) 
		retIntError();

	/* Perform the test sign/sig.check of the FIPS 186 test values */
	status = contextInfo.capabilityInfo->initKeyFunction( &contextInfo, NULL, 0 );
	if( cryptStatusOK( status ) && \
		!pairwiseConsistencyTest( &contextInfo ) )
		status = CRYPT_ERROR_FAILED;

	/* Clean up */
	staticDestroyContext( &contextInfo );

	return( status );
	}
#else
	#define selfTest	NULL
#endif /* !CONFIG_NO_SELFTEST */

/****************************************************************************
*																			*
*							Create/Check a Signature						*
*																			*
****************************************************************************/

/* Since DSA signature generation produces two values and the cryptEncrypt()
   model only provides for passing a byte string in and out (or, more
   specifically, the internal bignum data can't be exported to the outside
   world) we need to encode the resulting data into a flat format.  This is
   done by encoding the output as an X9.31 Dss-Sig record:

	Dss-Sig ::= SEQUENCE {
		r	INTEGER,
		s	INTEGER
		}

   The input is the 160-bit hash, usually SHA but possibly also RIPEMD-160 */

/* The size of each DSA signature component - 160 bits */

#define DSA_SIGPART_SIZE	20

/* Sign a single block of data  */

static int sign( CONTEXT_INFO *contextInfoPtr, BYTE *buffer, int noBytes )
	{
	PKC_INFO *pkcInfo = contextInfoPtr->ctxPKC;
	DLP_PARAMS *dlpParams = ( DLP_PARAMS * ) buffer;
	BIGNUM *p = &pkcInfo->dlpParam_p, *q = &pkcInfo->dlpParam_q;
	BIGNUM *g = &pkcInfo->dlpParam_g, *x = &pkcInfo->dlpParam_x;
	BIGNUM *hash = &pkcInfo->tmp1, *k = &pkcInfo->tmp2, *kInv = &pkcInfo->tmp3;
	BIGNUM *r = &pkcInfo->dlpTmp1, *s = &pkcInfo->dlpTmp2;
	int bnStatus = BN_STATUS, status;

	assert( noBytes == sizeof( DLP_PARAMS ) );
	assert( isReadPtr( dlpParams->inParam1, dlpParams->inLen1 ) );
	assert( dlpParams->inLen1 == DSA_SIGPART_SIZE );
	assert( dlpParams->inParam2 == NULL && \
			( dlpParams->inLen2 == 0 || dlpParams->inLen2 == -999 ) );
	assert( isWritePtr( dlpParams->outParam, dlpParams->outLen ) );
	assert( dlpParams->outLen >= ( 2 + DSA_SIGPART_SIZE ) * 2 );

	/* Generate the secret random value k.  During the initial self-test
	   the random data pool may not exist yet, and may in fact never exist in
	   a satisfactory condition if there isn't enough randomness present in
	   the system to generate cryptographically strong random numbers.  To
	   bypass this problem, if the caller passes in a second length parameter
	   of -999 we know that it's an internal self-test call and use a fixed
	   bit pattern for k that avoids having to call generateBignum() (this
	   also means that we can use the FIPS 186 self-test value for k).  This 
	   is a somewhat ugly use of 'magic numbers', but it's safe because this
	   function can only be called internally, so all we need to trap is
	   accidental use of the parameter which is normally unused */
	if( dlpParams->inLen2 == -999 )
		{
		status = importBignum( k, ( BYTE * ) kVal, DSA_SIGPART_SIZE,
							   DSA_SIGPART_SIZE, DSA_SIGPART_SIZE, NULL, 
							   SHORTKEY_CHECK_NONE );
		}
	else
		{
		/* Generate the random value k.  FIPS 186 requires (Appendix 3)
		   that this be done with:

			k = G(t,KKEY) mod q

		   where G(t,c) produces a 160-bit output, however this produces a
		   slight bias in k that leaks a small amount of the private key in
		   each signature.  Because of this we start with a value which is
		   32 bits larger than q and then do the reduction, eliminating the
		   bias.
		   
		   In theory we could also add (meaning "mix in" rather than 
		   strictly "arithmetically add") the message hash to k to curtail 
		   problems where the RNG value repeats, but the heavy-duty self-
		   checking of the RNG makes it somewhat unlikely that this 
		   condition would go undetected.  The one time when this can occur 
		   is when we're running in a VM and get rolled back, but it seems a 
		   bit uncertain how far down we want to chase this: at how many 
		   other locations in the code do we need to include Rube Goldberg 
		   protections against rollback?  Under what conditions can rollback 
		   occur?  When can rollback occur? */
		status = generateBignum( k, bytesToBits( DSA_SIGPART_SIZE ) + 32,
								 0x80, 0 );
		}
	if( cryptStatusError( status ) )
		return( status );
	if( contextInfoPtr->flags & CONTEXT_FLAG_SIDECHANNELPROTECTION )
		{
		/* Use constant-time modexp() to protect the secret random value 
		   from timing channels.  We could also use blinding, but neither of
		   these measures are actually terribly useful because we're using a 
		   random exponent each time so the timing information isn't of much
		   use to an attacker */
		BN_set_flags( k, BN_FLG_EXP_CONSTTIME );
		}
	CK( BN_mod( k, k, q, 				/* Reduce k to the correct range */
				pkcInfo->bnCTX ) );
	if( bnStatusError( bnStatus ) )
		return( getBnStatus( bnStatus ) );

	/* Make sure that the result isn't zero (or more generally less than 64
	   bits).  Admittedly the chances of this are infinitesimally small 
	   (2^-160 or less for a value of zero, 2^-96 for 64 bits) but someone's 
	   bound to complain if we don't check */
	ENSURES( BN_num_bytes( k ) > 8 );

	/* Get the hash as a bignum.  The range checking for the resulting value 
	   is a bit odd, we need to take "the leftmost sizeof( q ) bits of the 
	   hash" as the input, to handle this we require that the bit size of q 
	   be at least as large as the (nominal) bit size of the hash */
	if( dlpParams->inLen1 > BN_num_bytes( q ) )
		return( CRYPT_ERROR_BADDATA );
	status = importBignum( hash, ( BYTE * ) dlpParams->inParam1, 
						   DSA_SIGPART_SIZE, DSA_SIGPART_SIZE / 2, 
						   DSA_SIGPART_SIZE, NULL, SHORTKEY_CHECK_NONE );
	if( cryptStatusError( status ) )
		return( status );

	/* r = ( g ^ k mod p ) mod q */
	CK( BN_mod_exp_mont( r, g, k, p, pkcInfo->bnCTX,
						 &pkcInfo->dlpParam_mont_p ) );
	CK( BN_mod( r, r, q, pkcInfo->bnCTX ) );
	if( bnStatusError( bnStatus ) )
		return( getBnStatus( bnStatus ) );

	/* s = k^-1 * ( hash + x * r ) mod q */
	CKPTR( BN_mod_inverse( kInv, k, q,	/* temp = k^-1 mod q */
						   pkcInfo->bnCTX ) );
	CK( BN_mod_mul( s, x, r, q,			/* s = ( x * r ) mod q */
					pkcInfo->bnCTX ) );
	CK( BN_add( s, s, hash ) );			/* s = s + hash */
	if( BN_cmp( s, q ) > 0 )			/* if s > q */
		CK( BN_sub( s, s, q ) );		/*   s = s - q (fast mod) */
	CK( BN_mod_mul( s, s, kInv, q,		/* s = k^-1 * ( hash + x * r ) mod q */
					pkcInfo->bnCTX ) );
	if( bnStatusError( bnStatus ) )
		return( getBnStatus( bnStatus ) );

	/* Check that neither r = 0 or s = 0.  See the earlier comment where k 
	   is  checked for the real necessity of this check */
	ENSURES( !BN_is_zero( r ) && !BN_is_zero( s ) );

	/* Encode the result as a DL data block */
	status = pkcInfo->encodeDLValuesFunction( dlpParams->outParam, 
									dlpParams->outLen, &dlpParams->outLen, 
									r, s, dlpParams->formatType );
	if( cryptStatusError( status ) )
		return( status );

	/* Perform side-channel attack checks if necessary */
	if( ( contextInfoPtr->flags & CONTEXT_FLAG_SIDECHANNELPROTECTION ) && \
		cryptStatusError( calculateBignumChecksum( pkcInfo, 
												   CRYPT_ALGO_DSA ) ) )
		{
		return( CRYPT_ERROR_FAILED );
		}
	return( CRYPT_OK );
	}

/* Signature check a single block of data */

static int sigCheck( CONTEXT_INFO *contextInfoPtr, BYTE *buffer, int noBytes )
	{
	PKC_INFO *pkcInfo = contextInfoPtr->ctxPKC;
	DLP_PARAMS *dlpParams = ( DLP_PARAMS * ) buffer;
	BIGNUM *p = &pkcInfo->dlpParam_p, *q = &pkcInfo->dlpParam_q;
	BIGNUM *g = &pkcInfo->dlpParam_g, *y = &pkcInfo->dlpParam_y;
	BIGNUM *r = &pkcInfo->tmp1, *s = &pkcInfo->tmp2;
	BIGNUM *u1 = &pkcInfo->tmp3, *u2 = &pkcInfo->dlpTmp1;	/* Doubles as w */
	int bnStatus = BN_STATUS, status;

	assert( noBytes == sizeof( DLP_PARAMS ) );
	assert( isReadPtr( dlpParams->inParam1, dlpParams->inLen1 ) );
	assert( dlpParams->inLen1 == 20 );
	assert( isReadPtr( dlpParams->inParam2, dlpParams->inLen2 ) );
	assert( ( dlpParams->formatType == CRYPT_FORMAT_CRYPTLIB && \
			  ( dlpParams->inLen2 >= 42 && dlpParams->inLen2 <= 128 ) ) || \
			( dlpParams->formatType == CRYPT_FORMAT_PGP && \
			  ( dlpParams->inLen2 >= 42 && dlpParams->inLen2 <= 44 ) ) || \
			( dlpParams->formatType == CRYPT_IFORMAT_SSH && \
			  dlpParams->inLen2 == 40 ) );
	assert( dlpParams->outParam == NULL && dlpParams->outLen == 0 );

	/* Decode the values from a DL data block and make sure that r and s are
	   valid, i.e. r, s = [1...q-1] */
	status = pkcInfo->decodeDLValuesFunction( dlpParams->inParam2, 
											  dlpParams->inLen2, r, s, q,
											  dlpParams->formatType );
	if( cryptStatusError( status ) )
		return( status );

	/* Get the hash as a bignum.  The range checking for the resulting value 
	   is a bit odd, we need to take "the leftmost sizeof( q ) bits of the 
	   hash" as the input, to handle this we require that the bit size of q 
	   be at least as large as the (nominal) bit size of the hash */
	if( dlpParams->inLen1 > BN_num_bytes( q ) )
		return( CRYPT_ERROR_BADDATA );
	status = importBignum( u1, ( BYTE * ) dlpParams->inParam1, 
						   DSA_SIGPART_SIZE, DSA_SIGPART_SIZE / 2, 
						   DSA_SIGPART_SIZE, NULL, SHORTKEY_CHECK_NONE );
	if( cryptStatusError( status ) )
		return( status );

	/* w = s^-1 mod q */
	CKPTR( BN_mod_inverse( u2, s, q,	/* w = s^-1 mod q */
						   pkcInfo->bnCTX ) );
	if( bnStatusError( bnStatus ) )
		return( getBnStatus( bnStatus ) );

	/* u1 = ( hash * w ) mod q */
	CK( BN_mod_mul( u1, u1, u2, q,		/* u1 = ( hash * w ) mod q */
					pkcInfo->bnCTX ) );
	if( bnStatusError( bnStatus ) )
		return( getBnStatus( bnStatus ) );

	/* u2 = ( r * w ) mod q */
	CK( BN_mod_mul( u2, r, u2, q,		/* u2 = ( r * w ) mod q */
					pkcInfo->bnCTX ) );
	if( bnStatusError( bnStatus ) )
		return( getBnStatus( bnStatus ) );

	/* v = ( ( ( g^u1 ) * ( y^u2 ) ) mod p ) mod q */
	CK( BN_mod_exp2_mont( u2, g, u1, y, u2, p, pkcInfo->bnCTX,
						  &pkcInfo->dlpParam_mont_p ) );
	CK( BN_mod( s, u2, q, pkcInfo->bnCTX ) );
	if( bnStatusError( bnStatus ) )
		return( getBnStatus( bnStatus ) );

	/* If r == s then the signature is good */
	if( BN_cmp( r, s ) )
		return( CRYPT_ERROR_SIGNATURE );

	/* Perform side-channel attack checks if necessary */
	if( ( contextInfoPtr->flags & CONTEXT_FLAG_SIDECHANNELPROTECTION ) && \
		cryptStatusError( calculateBignumChecksum( pkcInfo, 
												   CRYPT_ALGO_DSA ) ) )
		{
		return( CRYPT_ERROR_FAILED );
		}
	return( CRYPT_OK );
	}

/****************************************************************************
*																			*
*								Key Management								*
*																			*
****************************************************************************/

/* Load key components into an encryption context */

static int initKey( CONTEXT_INFO *contextInfoPtr, const void *key,
					const int keyLength )
	{
	int status;

#ifndef USE_FIPS140
	/* Load the key component from the external representation into the
	   internal bignums unless we're doing an internal load */
	if( key != NULL )
		{
		PKC_INFO *pkcInfo = contextInfoPtr->ctxPKC;
		const CRYPT_PKCINFO_DLP *dsaKey = ( CRYPT_PKCINFO_DLP * ) key;

		contextInfoPtr->flags |= ( dsaKey->isPublicKey ) ? \
					CONTEXT_FLAG_ISPUBLICKEY : CONTEXT_FLAG_ISPRIVATEKEY;
		status = importBignum( &pkcInfo->dlpParam_p, dsaKey->p, 
							   bitsToBytes( dsaKey->pLen ),
							   DLPPARAM_MIN_P, DLPPARAM_MAX_P, NULL, 
							   SHORTKEY_CHECK_PKC );
		if( cryptStatusOK( status ) )
			status = importBignum( &pkcInfo->dlpParam_q, dsaKey->q, 
								   bitsToBytes( dsaKey->qLen ),
								   DLPPARAM_MIN_Q, DLPPARAM_MAX_Q, 
								   &pkcInfo->dlpParam_p, 
								   SHORTKEY_CHECK_NONE );
		if( cryptStatusOK( status ) )
			status = importBignum( &pkcInfo->dlpParam_g, dsaKey->g, 
								   bitsToBytes( dsaKey->gLen ),
								   DLPPARAM_MIN_G, DLPPARAM_MAX_G,
								   &pkcInfo->dlpParam_p, 
								   SHORTKEY_CHECK_NONE );
		if( cryptStatusOK( status ) )
			status = importBignum( &pkcInfo->dlpParam_y, dsaKey->y, 
								   bitsToBytes( dsaKey->yLen ),
								   DLPPARAM_MIN_Y, DLPPARAM_MAX_Y,
								   &pkcInfo->dlpParam_p, 
								   SHORTKEY_CHECK_NONE );
		if( cryptStatusOK( status ) && !dsaKey->isPublicKey )
			status = importBignum( &pkcInfo->dlpParam_x, dsaKey->x, 
								   bitsToBytes( dsaKey->xLen ),
								   DLPPARAM_MIN_X, DLPPARAM_MAX_X,
								   &pkcInfo->dlpParam_p, 
								   SHORTKEY_CHECK_NONE );
		contextInfoPtr->flags |= CONTEXT_FLAG_PBO;
		if( cryptStatusError( status ) )
			return( status );
		}
#endif /* USE_FIPS140 */

	/* Complete the key checking and setup */
	return( initCheckDLPkey( contextInfoPtr, FALSE, FALSE ) );
	}

/* Generate a key into an encryption context */

static int generateKey( CONTEXT_INFO *contextInfoPtr, const int keySizeBits )
	{
	int status;

	status = generateDLPkey( contextInfoPtr, ( keySizeBits / 64 ) * 64 );
	if( cryptStatusOK( status ) &&
#ifndef USE_FIPS140
		( contextInfoPtr->flags & CONTEXT_FLAG_SIDECHANNELPROTECTION ) &&
#endif /* USE_FIPS140 */
		!pairwiseConsistencyTest( contextInfoPtr ) )
		{
		DEBUG_DIAG(( "Consistency check of freshly-generated DSA key "
					 "failed" ));
		assert( DEBUG_WARN );
		status = CRYPT_ERROR_FAILED;
		}
	return( status );
	}

/****************************************************************************
*																			*
*						Capability Access Routines							*
*																			*
****************************************************************************/

static const CAPABILITY_INFO FAR_BSS capabilityInfo = {
	CRYPT_ALGO_DSA, bitsToBytes( 0 ), "DSA", 3,
	MIN_PKCSIZE, bitsToBytes( 1024 ), CRYPT_MAX_PKCSIZE,
	selfTest, getDefaultInfo, NULL, NULL, initKey, generateKey,
	NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, 
	sign, sigCheck
	};

const CAPABILITY_INFO *getDSACapability( void )
	{
	return( &capabilityInfo );
	}
