/**

 * \file poly1305.c

 *

 * \brief Poly1305 authentication algorithm.

 *

 *  Copyright The Mbed TLS Contributors

 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later

 */

#include "common.h"

#if defined(MBEDTLS_POLY1305_C)

#include "mbedtls/poly1305.h"

#include "mbedtls/platform_util.h"

#include "mbedtls/error.h"

#include <string.h>

#include "mbedtls/platform.h"

#if !defined(MBEDTLS_POLY1305_ALT)

#define POLY1305_BLOCK_SIZE_BYTES (16U)

/*

 * Our implementation is tuned for 32-bit platforms with a 64-bit multiplier.

 * However we provided an alternative for platforms without such a multiplier.

 */

#if defined(MBEDTLS_NO_64BIT_MULTIPLICATION)

static uint64_t mul64(uint32_t a, uint32_t b)

{

    /* a = al + 2**16 ah, b = bl + 2**16 bh */

    const uint16_t al = (uint16_t) a;

    const uint16_t bl = (uint16_t) b;

    const uint16_t ah = a >> 16;

    const uint16_t bh = b >> 16;

    /* ab = al*bl + 2**16 (ah*bl + bl*bh) + 2**32 ah*bh */

    const uint32_t lo = (uint32_t) al * bl;

    const uint64_t me = (uint64_t) ((uint32_t) ah * bl) + (uint32_t) al * bh;

    const uint32_t hi = (uint32_t) ah * bh;

    return lo + (me << 16) + ((uint64_t) hi << 32);

}

#else

static inline uint64_t mul64(uint32_t a, uint32_t b)

{

    return (uint64_t) a * b;

}

#endif

/**

 * \brief                   Process blocks with Poly1305.

 *

 * \param ctx               The Poly1305 context.

 * \param nblocks           Number of blocks to process. Note that this

 *                          function only processes full blocks.

 * \param input             Buffer containing the input block(s).

 * \param needs_padding     Set to 0 if the padding bit has already been

 *                          applied to the input data before calling this

 *                          function.  Otherwise, set this parameter to 1.

 */

static void poly1305_process(mbedtls_poly1305_context *ctx,

                             size_t nblocks,

                             const unsigned char *input,

                             uint32_t needs_padding)

{

    uint64_t d0, d1, d2, d3;

    uint32_t acc0, acc1, acc2, acc3, acc4;

    uint32_t r0, r1, r2, r3;

    uint32_t rs1, rs2, rs3;

    size_t offset  = 0U;

    size_t i;

    r0 = ctx->r[0];

    r1 = ctx->r[1];

    r2 = ctx->r[2];

    r3 = ctx->r[3];

    rs1 = r1 + (r1 >> 2U);

    rs2 = r2 + (r2 >> 2U);

    rs3 = r3 + (r3 >> 2U);

    acc0 = ctx->acc[0];

    acc1 = ctx->acc[1];

    acc2 = ctx->acc[2];

    acc3 = ctx->acc[3];

    acc4 = ctx->acc[4];

    /* Process full blocks */

    for (i = 0U; i < nblocks; i++) {

        /* The input block is treated as a 128-bit little-endian integer */

        d0   = MBEDTLS_GET_UINT32_LE(input, offset + 0);

        d1   = MBEDTLS_GET_UINT32_LE(input, offset + 4);

        d2   = MBEDTLS_GET_UINT32_LE(input, offset + 8);

        d3   = MBEDTLS_GET_UINT32_LE(input, offset + 12);

        /* Compute: acc += (padded) block as a 130-bit integer */

        d0  += (uint64_t) acc0;

        d1  += (uint64_t) acc1 + (d0 >> 32U);

        d2  += (uint64_t) acc2 + (d1 >> 32U);

        d3  += (uint64_t) acc3 + (d2 >> 32U);

        acc0 = (uint32_t) d0;

        acc1 = (uint32_t) d1;

        acc2 = (uint32_t) d2;

        acc3 = (uint32_t) d3;

        acc4 += (uint32_t) (d3 >> 32U) + needs_padding;

        /* Compute: acc *= r */

        d0 = mul64(acc0, r0) +

             mul64(acc1, rs3) +

             mul64(acc2, rs2) +

             mul64(acc3, rs1);

        d1 = mul64(acc0, r1) +

             mul64(acc1, r0) +

             mul64(acc2, rs3) +

             mul64(acc3, rs2) +

             mul64(acc4, rs1);

        d2 = mul64(acc0, r2) +

             mul64(acc1, r1) +

             mul64(acc2, r0) +

             mul64(acc3, rs3) +

             mul64(acc4, rs2);

        d3 = mul64(acc0, r3) +

             mul64(acc1, r2) +

             mul64(acc2, r1) +

             mul64(acc3, r0) +

             mul64(acc4, rs3);

        acc4 *= r0;

        /* Compute: acc %= (2^130 - 5) (partial remainder) */

        d1 += (d0 >> 32);

        d2 += (d1 >> 32);

        d3 += (d2 >> 32);

        acc0 = (uint32_t) d0;

        acc1 = (uint32_t) d1;

        acc2 = (uint32_t) d2;

        acc3 = (uint32_t) d3;

        acc4 = (uint32_t) (d3 >> 32) + acc4;

        d0 = (uint64_t) acc0 + (acc4 >> 2) + (acc4 & 0xFFFFFFFCU);

        acc4 &= 3U;

        acc0 = (uint32_t) d0;

        d0 = (uint64_t) acc1 + (d0 >> 32U);

        acc1 = (uint32_t) d0;

        d0 = (uint64_t) acc2 + (d0 >> 32U);

        acc2 = (uint32_t) d0;

        d0 = (uint64_t) acc3 + (d0 >> 32U);

        acc3 = (uint32_t) d0;

        d0 = (uint64_t) acc4 + (d0 >> 32U);

        acc4 = (uint32_t) d0;

        offset    += POLY1305_BLOCK_SIZE_BYTES;

    }

    ctx->acc[0] = acc0;

    ctx->acc[1] = acc1;

    ctx->acc[2] = acc2;

    ctx->acc[3] = acc3;

    ctx->acc[4] = acc4;

}

/**

 * \brief                   Compute the Poly1305 MAC

 *

 * \param ctx               The Poly1305 context.

 * \param mac               The buffer to where the MAC is written. Must be

 *                          big enough to contain the 16-byte MAC.

 */

static void poly1305_compute_mac(const mbedtls_poly1305_context *ctx,

                                 unsigned char mac[16])

{

    uint64_t d;

    uint32_t g0, g1, g2, g3, g4;

    uint32_t acc0, acc1, acc2, acc3, acc4;

    uint32_t mask;

    uint32_t mask_inv;

    acc0 = ctx->acc[0];

    acc1 = ctx->acc[1];

    acc2 = ctx->acc[2];

    acc3 = ctx->acc[3];

    acc4 = ctx->acc[4];

    /* Before adding 's' we ensure that the accumulator is mod 2^130 - 5.

     * We do this by calculating acc - (2^130 - 5), then checking if

     * the 131st bit is set. If it is, then reduce: acc -= (2^130 - 5)

     */

    /* Calculate acc + -(2^130 - 5) */

    d  = ((uint64_t) acc0 + 5U);

    g0 = (uint32_t) d;

    d  = ((uint64_t) acc1 + (d >> 32));

    g1 = (uint32_t) d;

    d  = ((uint64_t) acc2 + (d >> 32));

    g2 = (uint32_t) d;

    d  = ((uint64_t) acc3 + (d >> 32));

    g3 = (uint32_t) d;

    g4 = acc4 + (uint32_t) (d >> 32U);

    /* mask == 0xFFFFFFFF if 131st bit is set, otherwise mask == 0 */

    mask = (uint32_t) 0U - (g4 >> 2U);

    mask_inv = ~mask;

    /* If 131st bit is set then acc=g, otherwise, acc is unmodified */

    acc0 = (acc0 & mask_inv) | (g0 & mask);

    acc1 = (acc1 & mask_inv) | (g1 & mask);

    acc2 = (acc2 & mask_inv) | (g2 & mask);

    acc3 = (acc3 & mask_inv) | (g3 & mask);

    /* Add 's' */

    d = (uint64_t) acc0 + ctx->s[0];

    acc0 = (uint32_t) d;

    d = (uint64_t) acc1 + ctx->s[1] + (d >> 32U);

    acc1 = (uint32_t) d;

    d = (uint64_t) acc2 + ctx->s[2] + (d >> 32U);

    acc2 = (uint32_t) d;

    acc3 += ctx->s[3] + (uint32_t) (d >> 32U);

    /* Compute MAC (128 least significant bits of the accumulator) */

    MBEDTLS_PUT_UINT32_LE(acc0, mac,  0);

    MBEDTLS_PUT_UINT32_LE(acc1, mac,  4);

    MBEDTLS_PUT_UINT32_LE(acc2, mac,  8);

    MBEDTLS_PUT_UINT32_LE(acc3, mac, 12);

}

void mbedtls_poly1305_init(mbedtls_poly1305_context *ctx)

{

    mbedtls_platform_zeroize(ctx, sizeof(mbedtls_poly1305_context));

}

void mbedtls_poly1305_free(mbedtls_poly1305_context *ctx)

{

    if (ctx == NULL) {

        return;

    }

    mbedtls_platform_zeroize(ctx, sizeof(mbedtls_poly1305_context));

}

int mbedtls_poly1305_starts(mbedtls_poly1305_context *ctx,

                            const unsigned char key[32])

{

    /* r &= 0x0ffffffc0ffffffc0ffffffc0fffffff */

    ctx->r[0] = MBEDTLS_GET_UINT32_LE(key, 0)  & 0x0FFFFFFFU;

    ctx->r[1] = MBEDTLS_GET_UINT32_LE(key, 4)  & 0x0FFFFFFCU;

    ctx->r[2] = MBEDTLS_GET_UINT32_LE(key, 8)  & 0x0FFFFFFCU;

    ctx->r[3] = MBEDTLS_GET_UINT32_LE(key, 12) & 0x0FFFFFFCU;

    ctx->s[0] = MBEDTLS_GET_UINT32_LE(key, 16);

    ctx->s[1] = MBEDTLS_GET_UINT32_LE(key, 20);

    ctx->s[2] = MBEDTLS_GET_UINT32_LE(key, 24);

    ctx->s[3] = MBEDTLS_GET_UINT32_LE(key, 28);

    /* Initial accumulator state */

    ctx->acc[0] = 0U;

    ctx->acc[1] = 0U;

    ctx->acc[2] = 0U;

    ctx->acc[3] = 0U;

    ctx->acc[4] = 0U;

    /* Queue initially empty */

    mbedtls_platform_zeroize(ctx->queue, sizeof(ctx->queue));

    ctx->queue_len = 0U;

    return 0;

}

int mbedtls_poly1305_update(mbedtls_poly1305_context *ctx,

                            const unsigned char *input,

                            size_t ilen)

{

    size_t offset    = 0U;

    size_t remaining = ilen;

    size_t queue_free_len;

    size_t nblocks;

    if ((remaining > 0U) && (ctx->queue_len > 0U)) {

        queue_free_len = (POLY1305_BLOCK_SIZE_BYTES - ctx->queue_len);

        if (ilen < queue_free_len) {

            /* Not enough data to complete the block.

             * Store this data with the other leftovers.

             */

            memcpy(&ctx->queue[ctx->queue_len],

                   input,

                   ilen);

            ctx->queue_len += ilen;

            remaining = 0U;

        } else {

            /* Enough data to produce a complete block */

            memcpy(&ctx->queue[ctx->queue_len],

                   input,

                   queue_free_len);

            ctx->queue_len = 0U;

            poly1305_process(ctx, 1U, ctx->queue, 1U);   /* add padding bit */

            offset    += queue_free_len;

            remaining -= queue_free_len;

        }

    }

    if (remaining >= POLY1305_BLOCK_SIZE_BYTES) {

        nblocks = remaining / POLY1305_BLOCK_SIZE_BYTES;

        poly1305_process(ctx, nblocks, &input[offset], 1U);

        offset += nblocks * POLY1305_BLOCK_SIZE_BYTES;

        remaining %= POLY1305_BLOCK_SIZE_BYTES;

    }

    if (remaining > 0U) {

        /* Store partial block */

        ctx->queue_len = remaining;

        memcpy(ctx->queue, &input[offset], remaining);

    }

    return 0;

}

int mbedtls_poly1305_finish(mbedtls_poly1305_context *ctx,

                            unsigned char mac[16])

{

    /* Process any leftover data */

    if (ctx->queue_len > 0U) {

        /* Add padding bit */

        ctx->queue[ctx->queue_len] = 1U;

        ctx->queue_len++;

        /* Pad with zeroes */

        memset(&ctx->queue[ctx->queue_len],

               0,

               POLY1305_BLOCK_SIZE_BYTES - ctx->queue_len);

        poly1305_process(ctx, 1U,           /* Process 1 block */

                         ctx->queue, 0U);   /* Already padded above */

    }

    poly1305_compute_mac(ctx, mac);

    return 0;

}

int mbedtls_poly1305_mac(const unsigned char key[32],

                         const unsigned char *input,

                         size_t ilen,

                         unsigned char mac[16])

{

    mbedtls_poly1305_context ctx;

    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    mbedtls_poly1305_init(&ctx);

    ret = mbedtls_poly1305_starts(&ctx, key);

    if (ret != 0) {

        goto cleanup;

    }

    ret = mbedtls_poly1305_update(&ctx, input, ilen);

    if (ret != 0) {

        goto cleanup;

    }

    ret = mbedtls_poly1305_finish(&ctx, mac);

cleanup:

    mbedtls_poly1305_free(&ctx);

    return ret;

}

#endif /* MBEDTLS_POLY1305_ALT */

#if defined(MBEDTLS_SELF_TEST)

static const unsigned char test_keys[2][32] =

{

    {

        0x85, 0xd6, 0xbe, 0x78, 0x57, 0x55, 0x6d, 0x33,

        0x7f, 0x44, 0x52, 0xfe, 0x42, 0xd5, 0x06, 0xa8,

        0x01, 0x03, 0x80, 0x8a, 0xfb, 0x0d, 0xb2, 0xfd,

        0x4a, 0xbf, 0xf6, 0xaf, 0x41, 0x49, 0xf5, 0x1b

    },

    {

        0x1c, 0x92, 0x40, 0xa5, 0xeb, 0x55, 0xd3, 0x8a,

        0xf3, 0x33, 0x88, 0x86, 0x04, 0xf6, 0xb5, 0xf0,

        0x47, 0x39, 0x17, 0xc1, 0x40, 0x2b, 0x80, 0x09,

        0x9d, 0xca, 0x5c, 0xbc, 0x20, 0x70, 0x75, 0xc0

    }

};

static const unsigned char test_data[2][127] =

{

    {

        0x43, 0x72, 0x79, 0x70, 0x74, 0x6f, 0x67, 0x72,

        0x61, 0x70, 0x68, 0x69, 0x63, 0x20, 0x46, 0x6f,

        0x72, 0x75, 0x6d, 0x20, 0x52, 0x65, 0x73, 0x65,

        0x61, 0x72, 0x63, 0x68, 0x20, 0x47, 0x72, 0x6f,

        0x75, 0x70

    },

    {

        0x27, 0x54, 0x77, 0x61, 0x73, 0x20, 0x62, 0x72,

        0x69, 0x6c, 0x6c, 0x69, 0x67, 0x2c, 0x20, 0x61,

        0x6e, 0x64, 0x20, 0x74, 0x68, 0x65, 0x20, 0x73,

        0x6c, 0x69, 0x74, 0x68, 0x79, 0x20, 0x74, 0x6f,

        0x76, 0x65, 0x73, 0x0a, 0x44, 0x69, 0x64, 0x20,

        0x67, 0x79, 0x72, 0x65, 0x20, 0x61, 0x6e, 0x64,

        0x20, 0x67, 0x69, 0x6d, 0x62, 0x6c, 0x65, 0x20,

        0x69, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x77,

        0x61, 0x62, 0x65, 0x3a, 0x0a, 0x41, 0x6c, 0x6c,

        0x20, 0x6d, 0x69, 0x6d, 0x73, 0x79, 0x20, 0x77,

        0x65, 0x72, 0x65, 0x20, 0x74, 0x68, 0x65, 0x20,

        0x62, 0x6f, 0x72, 0x6f, 0x67, 0x6f, 0x76, 0x65,

        0x73, 0x2c, 0x0a, 0x41, 0x6e, 0x64, 0x20, 0x74,

        0x68, 0x65, 0x20, 0x6d, 0x6f, 0x6d, 0x65, 0x20,

        0x72, 0x61, 0x74, 0x68, 0x73, 0x20, 0x6f, 0x75,

        0x74, 0x67, 0x72, 0x61, 0x62, 0x65, 0x2e

    }

};

static const size_t test_data_len[2] =

{

    34U,

    127U

};

static const unsigned char test_mac[2][16] =

{

    {

        0xa8, 0x06, 0x1d, 0xc1, 0x30, 0x51, 0x36, 0xc6,

        0xc2, 0x2b, 0x8b, 0xaf, 0x0c, 0x01, 0x27, 0xa9

    },

    {

        0x45, 0x41, 0x66, 0x9a, 0x7e, 0xaa, 0xee, 0x61,

        0xe7, 0x08, 0xdc, 0x7c, 0xbc, 0xc5, 0xeb, 0x62

    }

};

/* Make sure no other definition is already present. */

#undef ASSERT

#define ASSERT(cond, args)            \

    do                                  \

    {                                   \

        if (!(cond))                \

        {                               \

            if (verbose != 0)          \

            mbedtls_printf args;    \

                                        \

            return -1;               \

        }                               \

    }                                   \

    while (0)

int mbedtls_poly1305_self_test(int verbose)

{

    unsigned char mac[16];

    unsigned i;

    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    for (i = 0U; i < 2U; i++) {

        if (verbose != 0) {

            mbedtls_printf("  Poly1305 test %u ", i);

        }

        ret = mbedtls_poly1305_mac(test_keys[i],

                                   test_data[i],

                                   test_data_len[i],

                                   mac);

        ASSERT(0 == ret, ("error code: %i\n", ret));

        ASSERT(0 == memcmp(mac, test_mac[i], 16U), ("failed (mac)\n"));

        if (verbose != 0) {

            mbedtls_printf("passed\n");

        }

    }

    if (verbose != 0) {

        mbedtls_printf("\n");

    }

    return 0;

}

#endif /* MBEDTLS_SELF_TEST */

#endif /* MBEDTLS_POLY1305_C */