Add GCM, CTR, and CTS modes to AES.

nss/mozilla/security/nss/lib/freebl/gcm.c

+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifdef FREEBL_NO_DEPEND
+#include "stubs.h"
+#endif
+#include "blapii.h"
+#include "blapit.h"
+#include "gcm.h"
+#include "ctr.h"
+#include "secerr.h"
+#include "prtypes.h"
+#include "pkcs11t.h"
+
+#include <limits.h>
+
+/**************************************************************************
+ *          First implement the Galois hash function of GCM (gcmHash)     *
+ **************************************************************************/
+#define GCM_HASH_LEN_LEN 8 /* gcm hash defines lengths to be 64 bits */
+
+typedef struct gcmHashContextStr gcmHashContext;
+
+static SECStatus gcmHash_InitContext(gcmHashContext *hash,
+                                     const unsigned char *H,
+                                     unsigned int blocksize);
+static void gcmHash_DestroyContext(gcmHashContext *ghash, PRBool freeit);
+static SECStatus gcmHash_Update(gcmHashContext *ghash,
+                                const unsigned char *buf, unsigned int len,
+                                unsigned int blocksize);
+static SECStatus gcmHash_Sync(gcmHashContext *ghash, unsigned int blocksize);
+static SECStatus gcmHash_Final(gcmHashContext *gcm, unsigned char *outbuf,
+                               unsigned int *outlen, unsigned int maxout,
+                               unsigned int blocksize);
+static SECStatus gcmHash_Reset(gcmHashContext *ghash,
+                               const unsigned char *inbuf,
+                               unsigned int inbufLen, unsigned int blocksize);
+
+/* compile time defines to select how the GF2 multiply is calculated.
+ * There are currently 2 algorithms implemented here: MPI and ALGORITHM_1.
+ *
+ * MPI uses the GF2m implemented in mpi to support GF2 ECC.
+ * ALGORITHM_1 is the Algorithm 1 in both NIST SP 800-38D and
+ * "The Galois/Counter Mode of Operation (GCM)", McGrew & Viega.
+ */
+#if !defined(GCM_USE_ALGORITHM_1) && !defined(GCM_USE_MPI)
+#define GCM_USE_MPI 1 /* MPI is about 5x faster with the
+                       * same or less complexity. It's possible to use
+                       * tables to speed things up even more */
+#endif
+
+/* GCM defines the bit string to be LSB first, which is exactly
+ * opposite everyone else, including hardware. build array
+ * to reverse everything. */
+static const unsigned char gcm_byte_rev[256] = {
+    0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0,
+    0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
+    0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
+    0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8,
+    0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4,
+    0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
+    0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec,
+    0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc,
+    0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
+    0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2,
+    0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea,
+    0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
+    0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6,
+    0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6,
+    0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
+    0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe,
+    0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1,
+    0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
+    0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9,
+    0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9,
+    0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
+    0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5,
+    0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed,
+    0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
+    0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3,
+    0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3,
+    0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
+    0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb,
+    0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7,
+    0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
+    0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef,
+    0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff
+};
+
+
+#ifdef GCM_TRACE
+#include <stdio.h>
+
+#define GCM_TRACE_X(ghash,label) { \
+        unsigned char _X[MAX_BLOCK_SIZE]; int i; \
+        gcm_getX(ghash, _X, blocksize); \
+        printf(label,(ghash)->m); \
+        for (i=0; i < blocksize; i++) printf("%02x",_X[i]); \
+        printf("\n"); }
+#define GCM_TRACE_BLOCK(label,buf,blocksize) {\
+        printf(label); \
+        for (i=0; i < blocksize; i++) printf("%02x",buf[i]); \
+        printf("\n"); }
+#else
+#define GCM_TRACE_X(ghash,label)
+#define GCM_TRACE_BLOCK(label,buf,blocksize)
+#endif
+
+#ifdef GCM_USE_MPI
+
+#ifdef GCM_USE_ALGORITHM_1
+#error "Only define one of GCM_USE_MPI, GCM_USE_ALGORITHM_1"
+#endif
+/* use the MPI functions to calculate Xn = (Xn-1^C_i)*H mod poly */
+#include "mpi.h"
+#include "secmpi.h"
+#include "mplogic.h"
+#include "mp_gf2m.h"
+
+/* state needed to handle GCM Hash function */
+struct gcmHashContextStr {
+     mp_int H;
+     mp_int X;
+     mp_int C_i;
+     unsigned int *poly;
+     unsigned long cLen;
+     unsigned char buffer[MAX_BLOCK_SIZE];
+     unsigned int bufLen;
+     int m; /* XXX what is m? */
+     unsigned char counterBuf[2*GCM_HASH_LEN_LEN];
+};
+
+/* f = x^128 + x^7 + x^2 + x + 1 */
+static unsigned int poly_128[] = { 128, 7, 2, 1, 0 };
+/* f = x^64 + x^4 + x^3 + x + 1 */
+static unsigned int poly_64[] = { 64, 4, 3, 1, 0 };
+
+/* sigh, GCM defines the bit strings exactly backwards from everything else */
+static void
+gcm_reverse(unsigned char *target, const unsigned char *src,
+                                                        unsigned int blocksize)
+{
+    unsigned int i;
+    for (i=0; i < blocksize; i++) {
+        target[blocksize-i-1] = gcm_byte_rev[src[i]];
+    }
+}
+
+/* Initialize a gcmHashContext */
+static SECStatus
+gcmHash_InitContext(gcmHashContext *ghash, const unsigned char *H,
+                    unsigned int blocksize)
+{
+    mp_err err = MP_OKAY;
+    unsigned char H_rev[MAX_BLOCK_SIZE];
+
+    MP_DIGITS(&ghash->H) = 0;
+    MP_DIGITS(&ghash->X) = 0;
+    MP_DIGITS(&ghash->C_i) = 0;
+    CHECK_MPI_OK( mp_init(&ghash->H) );
+    CHECK_MPI_OK( mp_init(&ghash->X) );
+    CHECK_MPI_OK( mp_init(&ghash->C_i) );
+
+    mp_zero(&ghash->X);
+    gcm_reverse(H_rev, H, blocksize);
+    CHECK_MPI_OK( mp_read_unsigned_octets(&ghash->H, H_rev, blocksize) );
+
+    /* set the irreducible polynomial. Each blocksize has its own polynomial.
+     * for now only blocksizes 16 (=128 bits) and 8 (=64 bits) are defined */
+    switch (blocksize) {
+    case 16: /* 128 bits */
+        ghash->poly = poly_128;
+        break;
+    case 8: /* 64 bits */
+        ghash->poly = poly_64;
+        break;
+    default:
+        PORT_SetError(SEC_ERROR_INVALID_ARGS);
+        goto cleanup;
+    }
+    ghash->cLen = 0;
+    ghash->bufLen = 0;
+    ghash->m = 0;
+    PORT_Memset(ghash->counterBuf, 0, sizeof(ghash->counterBuf));
+    return SECSuccess;
+cleanup:
+    gcmHash_DestroyContext(ghash, PR_FALSE);
+    return SECFailure;
+}
+
+/* Destroy a HashContext (Note we zero the digits so this function
+ * is idempotent if called with freeit == PR_FALSE */
+static void
+gcmHash_DestroyContext(gcmHashContext *ghash, PRBool freeit)
+{
+    mp_clear(&ghash->H);
+    mp_clear(&ghash->X);
+    mp_clear(&ghash->C_i);
+    MP_DIGITS(&ghash->H) = 0;
+    MP_DIGITS(&ghash->X) = 0;
+    MP_DIGITS(&ghash->C_i) = 0;
+    if (freeit) {
+        PORT_Free(ghash);
+    }
+}
+
+static SECStatus
+gcm_getX(gcmHashContext *ghash, unsigned char *T, unsigned int blocksize)
+{
+    int len;
+    mp_err err;
+    unsigned char tmp_buf[MAX_BLOCK_SIZE];
+    unsigned char *X;
+
+    len = mp_unsigned_octet_size(&ghash->X);
+    if (len <= 0) {
+        PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
+        return SECFailure;
+    }
+    X = tmp_buf;
+    PORT_Assert(len <= blocksize);
+    if (len > blocksize) {
+        PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
+        return SECFailure;
+    }
+    /* zero pad the result */
+    if (len != blocksize) {
+        PORT_Memset(X,0,blocksize-len);
+        X += blocksize-len;
+    }
+
+    err = mp_to_unsigned_octets(&ghash->X, X, len);
+    if (err < 0) {
+        PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
+        return SECFailure;
+    }
+    gcm_reverse(T, X, blocksize);
+    return SECSuccess;
+}
+
+static SECStatus
+gcm_HashMult(gcmHashContext *ghash, const unsigned char *buf,
+                unsigned int count, unsigned int blocksize)
+{
+    SECStatus rv = SECFailure;
+    mp_err err = MP_OKAY;
+    unsigned char tmp_buf[MAX_BLOCK_SIZE];
+    unsigned int i;
+
+    for (i=0; i < count; i++, buf += blocksize) {
+        ghash->m++;
+        gcm_reverse(tmp_buf, buf, blocksize);
+        CHECK_MPI_OK(mp_read_unsigned_octets(&ghash->C_i, tmp_buf, blocksize));
+        CHECK_MPI_OK(mp_badd(&ghash->X, &ghash->C_i, &ghash->C_i));
+        /*
+         * Looking to speed up GCM, this the the place to do it.
+         * There are two areas that can be exploited to speed up this code.
+         *
+         * 1) H is a constant in this multiply. We can precompute H * (0 - 255)
+         * at init time and this becomes an blockize xors of our table lookup.
+         *
+         * 2) poly is a constant for each blocksize. We can calculate the
+         * modulo reduction by a series of adds and shifts.
+         *
+         * For now we are after functionality, so we will go ahead and use
+         * the builtin bmulmod from mpi
+         */
+        CHECK_MPI_OK(mp_bmulmod(&ghash->C_i, &ghash->H,
+                                        ghash->poly, &ghash->X));
+        GCM_TRACE_X(ghash, "X%d = ")
+    }
+    rv = SECSuccess;
+cleanup:
+    if (rv != SECSuccess) {
+        MP_TO_SEC_ERROR(err);
+    }
+    return rv;
+}
+
+static void
+gcm_zeroX(gcmHashContext *ghash)
+{
+    mp_zero(&ghash->X);
+    ghash->m = 0;
+}
+
+#endif
+
+#ifdef GCM_USE_ALGORITHM_1
+/* use algorithm 1 of McGrew & Viega "The Galois/Counter Mode of Operation" */
+
+#define GCM_ARRAY_SIZE (MAX_BLOCK_SIZE/sizeof(unsigned long))
+
+struct gcmHashContextStr {
+     unsigned long H[GCM_ARRAY_SIZE];
+     unsigned long X[GCM_ARRAY_SIZE];
+     unsigned long R;
+     unsigned long cLen;
+     unsigned char buffer[MAX_BLOCK_SIZE];
+     unsigned int bufLen;
+     int m;
+     unsigned char counterBuf[2*GCM_HASH_LEN_LEN];
+};
+
+static void
+gcm_bytes_to_longs(unsigned long *l, const unsigned char *c, unsigned int len)
+{
+    int i,j;
+    int array_size = len/sizeof(unsigned long);
+
+    PORT_Assert(len % sizeof(unsigned long) == 0);
+    for (i=0; i < array_size; i++) {
+        unsigned long tmp = 0;
+        int byte_offset = i * sizeof(unsigned long);
+        for (j=sizeof(unsigned long)-1; j >= 0; j--) {
+            tmp = (tmp << PR_BITS_PER_BYTE) | gcm_byte_rev[c[byte_offset+j]];
+        }
+        l[i] = tmp;
+    }
+}
+
+static void
+gcm_longs_to_bytes(const unsigned long *l, unsigned char *c, unsigned int len)
+{
+    int i,j;
+    int array_size = len/sizeof(unsigned long);
+
+    PORT_Assert(len % sizeof(unsigned long) == 0);
+    for (i=0; i < array_size; i++) {
+        unsigned long tmp = l[i];
+        int byte_offset = i * sizeof(unsigned long);
+        for (j=0; j < sizeof(unsigned long); j++) {
+            c[byte_offset+j] = gcm_byte_rev[tmp & 0xff];
+            tmp = (tmp >> PR_BITS_PER_BYTE);
+        }
+    }
+}
+
+
+/* Initialize a gcmHashContext */
+static SECStatus
+gcmHash_InitContext(gcmHashContext *ghash, const unsigned char *H,
+                    unsigned int blocksize)
+{
+    PORT_Memset(ghash->X, 0, sizeof(ghash->X));
+    PORT_Memset(ghash->H, 0, sizeof(ghash->H));
+    gcm_bytes_to_longs(ghash->H, H, blocksize);
+
+    /* set the irreducible polynomial. Each blocksize has it's own polynommial
+     * for now only blocksizes 16 (=128 bits) and 8 (=64 bits) are defined */
+    switch (blocksize) {
+    case 16: /* 128 bits */
+        ghash->R = (unsigned long) 0x87; /* x^7 + x^2 + x +1 */
+        break;
+    case 8: /* 64 bits */
+        ghash->R = (unsigned long) 0x1b; /* x^4 + x^3 + x + 1 */
+        break;
+    default:
+        PORT_SetError(SEC_ERROR_INVALID_ARGS);
+        goto cleanup;
+    }
+    ghash->cLen = 0;
+    ghash->bufLen = 0;
+    ghash->m = 0;
+    PORT_Memset(ghash->counterBuf, 0, sizeof(ghash->counterBuf));
+    return SECSuccess;
+cleanup:
+    return SECFailure;
+}
+
+/* Destroy a HashContext (Note we zero the digits so this function
+ * is idempotent if called with freeit == PR_FALSE */
+static void
+gcmHash_DestroyContext(gcmHashContext *ghash, PRBool freeit)
+{
+    if (freeit) {
+        PORT_Free(ghash);
+    }
+}
+
+static unsigned long
+gcm_shift_one(unsigned long *t, int count)
+{
+    unsigned long carry = 0;
+    unsigned long nextcarry = 0;
+    int i;
+    for (i=0; i < count; i++) {
+        nextcarry = t[i] >> ((sizeof(unsigned long)*PR_BITS_PER_BYTE)-1);
+        t[i] = (t[i] << 1) | carry;
+        carry = nextcarry;
+    }
+    return carry;
+}
+
+static SECStatus
+gcm_getX(gcmHashContext *ghash, unsigned char *T, unsigned int blocksize)
+{
+    gcm_longs_to_bytes(ghash->X, T, blocksize);
+    return SECSuccess;
+}
+
+#define GCM_XOR(t, s, len) \
+        for (l=0; l < len; l++) t[l] ^= s[l]
+
+static SECStatus
+gcm_HashMult(gcmHashContext *ghash, const unsigned char *buf,
+                unsigned int count, unsigned int blocksize)
+{
+    unsigned long C_i[GCM_ARRAY_SIZE];
+    int arraysize = blocksize/sizeof(unsigned long);
+    int i, j, k, l;
+
+    for (i=0; i < count; i++, buf += blocksize) {
+        ghash->m++;
+        gcm_bytes_to_longs(C_i, buf, blocksize);
+        GCM_XOR(C_i, ghash->X, arraysize);
+        /* multiply X = C_i * H */
+        PORT_Memset(ghash->X, 0, sizeof(ghash->X));
+        for (j=0; j < arraysize; j++) {
+            unsigned long H = ghash->H[j];
+            for (k=0; k < sizeof(unsigned long)*PR_BITS_PER_BYTE; k++) {
+                if (H & 1) {
+                    GCM_XOR(ghash->X, C_i, arraysize);
+                }
+                if (gcm_shift_one(C_i, arraysize)) {
+                    C_i[0] = C_i[0] ^ ghash->R;
+                }
+                H = H >> 1;
+            }
+        }
+        GCM_TRACE_X(ghash, "X%d = ")
+    }
+    return SECSuccess;
+}
+
+
+static void
+gcm_zeroX(gcmHashContext *ghash)
+{
+    PORT_Memset(ghash->X, 0, sizeof(ghash->X));
+    ghash->m = 0;
+}
+#endif
+
+/*
+ * implement GCM GHASH using the freebl GHASH function. The gcm_HashMult
+ * function always takes blocksize lengths of data. gcmHash_Update will
+ * format the data properly.
+ */
+static SECStatus
+gcmHash_Update(gcmHashContext *ghash, const unsigned char *buf,
+               unsigned int len, unsigned int blocksize)
+{
+    unsigned int blocks;
+    SECStatus rv;
+
+    ghash->cLen += (len*PR_BITS_PER_BYTE);
+
+    /* first deal with the current buffer of data. Try to fill it out so
+     * we can hash it */
+    if (ghash->bufLen) {
+        unsigned int needed = PR_MIN(len, blocksize - ghash->bufLen);
+        PORT_Memcpy(ghash->buffer+ghash->bufLen, buf, needed);
+        buf += needed;
+        len -= needed;
+        ghash->bufLen += needed;
+        if (ghash->bufLen != blocksize) {

[wtc, 2012/09/14 01:16:42]

This test is equivalent to the original test (len == 0), but
this test makes it clearer that ghash->buffer now has a full
block of data that can be hashed.

If you think the original test is clearer, I'll change this
back.

[wtc, 2012/09/18 01:03:40]

I changed this back to if (len == 0).

+            /* didn't add enough to hash the data, nothing more do do */
+            PORT_Assert(len == 0);
+            return SECSuccess;
+        }
+        /* hash the buffer and clear it */
+        rv = gcm_HashMult(ghash, ghash->buffer, 1, blocksize);
+        PORT_Memset(ghash->buffer, 0, blocksize);
+        ghash->bufLen = 0;
+        if (rv != SECSuccess) {
+            return SECFailure;
+        }
+    }
+    /* now hash any full blocks remaining in the data stream */
+    blocks = len/blocksize;
+    if (blocks) {
+        rv = gcm_HashMult(ghash, buf, blocks, blocksize);
+        if (rv != SECSuccess) {
+            return SECFailure;
+        }
+        buf += blocks*blocksize;
+        len -= blocks*blocksize;
+    }
+
+    /* save any remainder in the buffer to be hashed with the next call */
+    if (len != 0) {
+        PORT_Memcpy(ghash->buffer, buf, len);
+        ghash->bufLen = len;
+    }
+    return SECSuccess;
+}
+
+/*
+ * write out any partial blocks zero padded through the GHASH engine,
+ * save the lengths for the final completion of the hash
+ */
+static SECStatus
+gcmHash_Sync(gcmHashContext *ghash, unsigned int blocksize)
+{
+    int i;
+    SECStatus rv;
+
+    /* copy the previous counter to the upper block */
+    PORT_Memcpy(ghash->counterBuf, &ghash->counterBuf[GCM_HASH_LEN_LEN],
+                                                        GCM_HASH_LEN_LEN);
+    /* copy the current counter in the lower block */
+    for (i=0; i < GCM_HASH_LEN_LEN; i++) {
+        ghash->counterBuf[GCM_HASH_LEN_LEN+i] =
+            (ghash->cLen >> ((GCM_HASH_LEN_LEN-1-i)*PR_BITS_PER_BYTE)) & 0xff;
+    }
+    ghash->cLen = 0;
+
+    /* now zero fill the buffer and hash the last block */
+    if (ghash->bufLen) {
+        PORT_Memset(ghash->buffer+ghash->bufLen, 0, blocksize - ghash->bufLen);
+        rv = gcm_HashMult(ghash, ghash->buffer, 1, blocksize);
+        PORT_Memset(ghash->buffer, 0, blocksize);
+        ghash->bufLen = 0;
+        if (rv != SECSuccess) {
+            return SECFailure;
+        }
+    }
+    return SECSuccess;
+}
+
+/*
+ * This does the final sync, hashes the lengths, then returns
+ * "T", the hashed output.
+ */
+static SECStatus
+gcmHash_Final(gcmHashContext *ghash, unsigned char *outbuf,
+                unsigned int *outlen, unsigned int maxout,
+                unsigned int blocksize)
+{
+    unsigned char T[MAX_BLOCK_SIZE];
+    SECStatus rv;
+
+    rv = gcmHash_Sync(ghash, blocksize);
+    if (rv != SECSuccess) {
+        return SECFailure;
+    }
+
+    rv = gcm_HashMult(ghash, ghash->counterBuf, (GCM_HASH_LEN_LEN*2)/blocksize,
+                                                                blocksize);
+    if (rv != SECSuccess) {
+        return SECFailure;
+    }
+
+    GCM_TRACE_X(ghash, "GHASH(H,A,C) = ")
+
+    rv = gcm_getX(ghash, T, blocksize);
+    if (rv != SECSuccess) {
+        return SECFailure;
+    }
+
+    if (maxout > blocksize) maxout = blocksize;
+    PORT_Memcpy(outbuf, T, maxout);
+    *outlen = maxout;
+    return SECSuccess;
+}
+
+SECStatus
+gcmHash_Reset(gcmHashContext *ghash, const unsigned char *AAD,
+              unsigned int AADLen, unsigned int blocksize)
+{
+    SECStatus rv;
+
+    ghash->cLen = 0;
+    PORT_Memset(ghash->counterBuf, 0, GCM_HASH_LEN_LEN*2);
+    ghash->bufLen = 0;
+    gcm_zeroX(ghash);
+
+    /* now kick things off by hashing the Additional Authenticated Data */
+    if (AADLen != 0) {
+        rv = gcmHash_Update(ghash, AAD, AADLen, blocksize);
+        if (rv != SECSuccess) {
+            return SECFailure;
+        }
+        rv = gcmHash_Sync(ghash, blocksize);
+        if (rv != SECSuccess) {
+            return SECFailure;
+        }
+    }
+    return SECSuccess;
+}
+
+/**************************************************************************
+ *           Now implement the GCM using gcmHash and CTR                  *
+ **************************************************************************/
+
+/* state to handle the full GCM operation (hash and counter) */
+struct GCMContextStr {
+    gcmHashContext ghash_context;
+    CTRContext ctr_context;
+    unsigned long tagBits;
+    unsigned char tagKey[MAX_BLOCK_SIZE];
+};
+
+GCMContext *
+GCM_CreateContext(void *context, freeblCipherFunc cipher,
+                  const unsigned char *params, unsigned int blocksize)
+{
+    GCMContext *gcm = NULL;
+    gcmHashContext *ghash;
+    unsigned char H[MAX_BLOCK_SIZE];
+    unsigned int tmp;
+    PRBool freeCtr = PR_FALSE;
+    PRBool freeHash = PR_FALSE;
+    const CK_AES_GCM_PARAMS *gcmParams = (const CK_AES_GCM_PARAMS *)params;
+    CK_AES_CTR_PARAMS ctrParams;
+    SECStatus rv;
+
+    if (blocksize > MAX_BLOCK_SIZE || blocksize > sizeof(ctrParams.cb)) {
+        PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
+        return NULL;
+    }
+    gcm = PORT_ZNew(GCMContext);
+    if (gcm == NULL) {
+        return NULL;
+    }
+    /* first fill in the ghash context */
+    ghash = &gcm->ghash_context;
+    PORT_Memset(H, 0, blocksize);
+    rv = (*cipher)(context, H, &tmp, blocksize, H, blocksize, blocksize);
+    if (rv != SECSuccess) {
+        goto loser;
+    }
+    rv = gcmHash_InitContext(ghash, H, blocksize);
+    if (rv != SECSuccess) {
+        goto loser;
+    }
+    freeHash = PR_TRUE;
+
+    /* fill in the Counter context */
+    ctrParams.ulCounterBits = 32;
+    PORT_Memset(ctrParams.cb, 0, sizeof(ctrParams.cb));
+    if ((blocksize == 8) && (gcmParams->ulIvLen == 4)) {
+        PORT_Memcpy(&ctrParams.cb[4], gcmParams->pIv, gcmParams->ulIvLen);
+    } else if ((blocksize == 16) && (gcmParams->ulIvLen == 12)) {
+        PORT_Memcpy(ctrParams.cb, gcmParams->pIv, gcmParams->ulIvLen);
+        ctrParams.cb[blocksize-1] = 1;
+    } else {
+        rv = gcmHash_Update(ghash, gcmParams->pIv, gcmParams->ulIvLen,
+                            blocksize);
+        if (rv != SECSuccess) {
+            goto loser;
+        }
+        rv = gcmHash_Final(ghash, ctrParams.cb, &tmp, blocksize, blocksize);
+        if (rv != SECSuccess) {
+            goto loser;
+        }
+    }
+    rv = CTR_InitContext(&gcm->ctr_context, context, cipher,
+                                (unsigned char *)&ctrParams, blocksize);
+    if (rv != SECSuccess) {
+        goto loser;
+    }
+    freeCtr = PR_TRUE;
+
+    /* fill in the gcm structure */
+    gcm->tagBits = gcmParams->ulTagBits; /* save for final step */
+    /* calculate the final tag key. NOTE: gcm->tagKey is zero to start with.
+     * if this assumption changes, we would need to explicitly clear it here */
+    rv = CTR_Update(&gcm->ctr_context, gcm->tagKey, &tmp, blocksize,
+                    gcm->tagKey, blocksize, blocksize);
+    if (rv != SECSuccess) {
+        goto loser;
+    }
+
+    /* finally mix in the AAD data */
+    rv = gcmHash_Reset(ghash, gcmParams->pAAD, gcmParams->ulAADLen, blocksize);
+    if (rv != SECSuccess) {
+        goto loser;
+    }
+
+    return gcm;
+
+loser:
+    if (freeCtr) {
+        CTR_DestroyContext(&gcm->ctr_context, PR_FALSE);
+    }
+    if (freeHash) {
+        gcmHash_DestroyContext(&gcm->ghash_context, PR_FALSE);
+    }
+    if (gcm) {
+        PORT_Free(gcm);
+    }
+    return NULL;
+}
+
+void
+GCM_DestroyContext(GCMContext *gcm, PRBool freeit)
+{
+    /* these two are statically allocated and will be freed when we free
+     * gcm. call their destroy functions to free up any locally
+     * allocated data (like mp_int's) */
+    CTR_DestroyContext(&gcm->ctr_context, PR_FALSE);
+    gcmHash_DestroyContext(&gcm->ghash_context, PR_FALSE);
+    if (freeit) {
+        PORT_Free(gcm);
+    }
+}
+
+static SECStatus
+gcm_GetTag(GCMContext *gcm, unsigned char *outbuf,
+        unsigned int *outlen, unsigned int maxout,
+        unsigned int blocksize)
+{
+    unsigned int tagBytes;
+    unsigned int extra;
+    unsigned int i;
+    SECStatus rv;
+
+    tagBytes = (gcm->tagBits + (PR_BITS_PER_BYTE-1)) / PR_BITS_PER_BYTE;
+    extra = tagBytes*PR_BITS_PER_BYTE - gcm->tagBits;
+
+    if (outbuf == NULL) {
+        *outlen = tagBytes;
+        PORT_SetError(SEC_ERROR_OUTPUT_LEN);
+        return SECFailure;
+    }
+
+    if (maxout < tagBytes) {
+        *outlen = tagBytes;
+        PORT_SetError(SEC_ERROR_OUTPUT_LEN);
+        return SECFailure;
+    }
+    maxout = tagBytes;
+    rv = gcmHash_Final(&gcm->ghash_context, outbuf, outlen, maxout, blocksize);
+    if (rv != SECSuccess) {
+        return SECFailure;
+    }
+
+    GCM_TRACE_BLOCK("GHASH=", outbuf, blocksize);
+    GCM_TRACE_BLOCK("Y0=", gcm->tagKey, blocksize);
+    for (i=0; i < *outlen; i++) {
+        outbuf[i] ^= gcm->tagKey[i];
+    }
+    GCM_TRACE_BLOCK("Y0=", gcm->tagKey, blocksize);
+    GCM_TRACE_BLOCK("T=", outbuf, blocksize);
+    /* mask off any extra bits we got */
+    if (extra) {
+        outbuf[tagBytes-1] &= ~((1 << extra)-1);
+    }
+    return SECSuccess;
+}
+
+
+/*
+ * See The Galois/Counter Mode of Operation, McGrew and Viega.
+ *  GCM is basically counter mode with a specific initialization and
+ *  built in macing operation.
+ */
+SECStatus
+GCM_EncryptUpdate(GCMContext *gcm, unsigned char *outbuf,
+                unsigned int *outlen, unsigned int maxout,
+                const unsigned char *inbuf, unsigned int inlen,
+                unsigned int blocksize)
+{
+    SECStatus rv;
+    unsigned int tagBytes;
+    unsigned int len;
+
+    tagBytes = (gcm->tagBits + (PR_BITS_PER_BYTE-1)) / PR_BITS_PER_BYTE;
+    if (UINT_MAX - inlen < tagBytes) {
+        PORT_SetError(SEC_ERROR_INPUT_LEN);
+        return SECFailure;
+    }
+    if (maxout < inlen + tagBytes) {
+        *outlen = inlen + tagBytes;
+        PORT_SetError(SEC_ERROR_OUTPUT_LEN);
+        return SECFailure;
+    }
+
+    rv = CTR_Update(&gcm->ctr_context, outbuf, outlen, maxout,
+                        inbuf, inlen, blocksize);
+    if (rv != SECSuccess) {
+        return SECFailure;
+    }
+    rv = gcmHash_Update(&gcm->ghash_context, outbuf, *outlen, blocksize);
+    if (rv != SECSuccess) {
+        PORT_Memset(outbuf, 0, *outlen); /* clear the output buffer */
+        *outlen = 0;
+        return SECFailure;
+    }
+    rv = gcm_GetTag(gcm, outbuf + *outlen, &len, maxout - *outlen, blocksize);
+    if (rv != SECSuccess) {
+        PORT_Memset(outbuf, 0, *outlen); /* clear the output buffer */
+        *outlen = 0;
+        return SECFailure;
+    };
+    *outlen += len;
+    return SECSuccess;
+}
+
+/*
+ * See The Galois/Counter Mode of Operation, McGrew and Viega.
+ *  GCM is basically counter mode with a specific initialization and
+ *  built in macing operation. NOTE: the only difference between Encrypt
+ *  and Decrypt is when we calculate the mac. That is because the mac must
+ *  always be calculated on the cipher text, not the plain text, so for
+ *  encrypt, we do the CTR update first and for decrypt we do the mac first.
+ */
+SECStatus
+GCM_DecryptUpdate(GCMContext *gcm, unsigned char *outbuf,
+                unsigned int *outlen, unsigned  int maxout,
+                const unsigned char *inbuf, unsigned int inlen,
+                unsigned int blocksize)
+{
+    SECStatus rv;
+    unsigned int tagBytes;
+    unsigned char tag[MAX_BLOCK_SIZE];
+    const unsigned char *intag;
+    unsigned int len;
+
+    tagBytes = (gcm->tagBits + (PR_BITS_PER_BYTE-1)) / PR_BITS_PER_BYTE;
+
+    /* get the authentication block */
+    if (inlen < tagBytes) {
+        PORT_SetError(SEC_ERROR_INVALID_ARGS);
+        return SECFailure;
+    }
+
+    inlen -= tagBytes;
+    intag = inbuf + inlen;
+
+    /* verify the block */
+    rv = gcmHash_Update(&gcm->ghash_context, inbuf, inlen, blocksize);
+    if (rv != SECSuccess) {
+        return SECFailure;
+    }
+    rv = gcm_GetTag(gcm, tag, &len, blocksize, blocksize);
+    if (rv != SECSuccess) {
+        return SECFailure;
+    }
+    /* Don't decrypt if we can't authenticate the encrypted data!
+     * This assumes that if tagBits is not a multiple of 8, intag will
+     * preserve the masked off missing bits.  */
+    if (NSS_SecureMemcmp(tag, intag, tagBytes) != 0) {
+        /* force a CKR_ENCRYPTED_DATA_INVALID error at in softoken */
+        PORT_SetError(SEC_ERROR_BAD_DATA);
+        return SECFailure;
+    }
+    /* finish the decryption */
+    return CTR_Update(&gcm->ctr_context, outbuf, outlen, maxout,
+                          inbuf, inlen, blocksize);
+}