size_t CRYPTO_ccm128_tag(CCM128_CONTEXT *ctx, unsigned char *tag, size_t len)
{
    unsigned int M = (ctx->nonce.c[0] >> 3) & 7;
    M *= 2;
    M += 2;
    if (len < M)
        return 0;
    memcpy(tag, ctx->cmac.c, M);
    return M;
}
['static int aes_ccm_ctrl(EVP_CIPHER_CTX *c, int type, int arg, void *ptr)\n{\n    EVP_AES_CCM_CTX *cctx = c->cipher_data;\n    switch (type) {\n    case EVP_CTRL_INIT:\n        cctx->key_set = 0;\n        cctx->iv_set = 0;\n        cctx->L = 8;\n        cctx->M = 12;\n        cctx->tag_set = 0;\n        cctx->len_set = 0;\n        return 1;\n    case EVP_CTRL_CCM_SET_IVLEN:\n        arg = 15 - arg;\n    case EVP_CTRL_CCM_SET_L:\n        if (arg < 2 || arg > 8)\n            return 0;\n        cctx->L = arg;\n        return 1;\n    case EVP_CTRL_CCM_SET_TAG:\n        if ((arg & 1) || arg < 4 || arg > 16)\n            return 0;\n        if ((c->encrypt && ptr) || (!c->encrypt && !ptr))\n            return 0;\n        if (ptr) {\n            cctx->tag_set = 1;\n            memcpy(c->buf, ptr, arg);\n        }\n        cctx->M = arg;\n        return 1;\n    case EVP_CTRL_CCM_GET_TAG:\n        if (!c->encrypt || !cctx->tag_set)\n            return 0;\n        if (!CRYPTO_ccm128_tag(&cctx->ccm, ptr, (size_t)arg))\n            return 0;\n        cctx->tag_set = 0;\n        cctx->iv_set = 0;\n        cctx->len_set = 0;\n        return 1;\n    case EVP_CTRL_COPY:\n        {\n            EVP_CIPHER_CTX *out = ptr;\n            EVP_AES_CCM_CTX *cctx_out = out->cipher_data;\n            if (cctx->ccm.key) {\n                if (cctx->ccm.key != &cctx->ks)\n                    return 0;\n                cctx_out->ccm.key = &cctx_out->ks;\n            }\n            return 1;\n        }\n    default:\n        return -1;\n    }\n}', 'size_t CRYPTO_ccm128_tag(CCM128_CONTEXT *ctx, unsigned char *tag, size_t len)\n{\n    unsigned int M = (ctx->nonce.c[0] >> 3) & 7;\n    M *= 2;\n    M += 2;\n    if (len < M)\n        return 0;\n    memcpy(tag, ctx->cmac.c, M);\n    return M;\n}']