Index: cipher/Makefile.am =================================================================== --- cipher/Makefile.am +++ cipher/Makefile.am @@ -50,6 +50,7 @@ cipher-cmac.c \ cipher-gcm.c cipher-gcm-intel-pclmul.c cipher-gcm-armv7-neon.S \ cipher-gcm-armv8-aarch32-ce.S cipher-gcm-armv8-aarch64-ce.S \ + cipher-gcm-ppc.c \ cipher-poly1305.c \ cipher-ocb.c \ cipher-xts.c \ @@ -251,3 +252,9 @@ crc-ppc.lo: $(srcdir)/crc-ppc.c Makefile `echo $(LTCOMPILE) $(ppc_vcrypto_cflags) -c $< | $(instrumentation_munging) ` + +cipher-gcm-ppc.o: $(srcdir)/cipher-gcm-ppc.c Makefile + `echo $(COMPILE) $(ppc_vcrypto_cflags) -c $< | $(instrumentation_munging) ` + +chiper-gcm-ppc.lo: $(srcdir)/cipher-gcm-ppc.c Makefile + `echo $(LTCOMPILE) $(ppc_vcrypto_cflags) -c $< | $(instrumentation_munging) ` Index: cipher/cipher-gcm-ppc.c =================================================================== --- /dev/null +++ cipher/cipher-gcm-ppc.c @@ -0,0 +1,442 @@ +/* cipher-gcm-gcm.c - Power 8 vpmsum accelerated Galois Counter Mode + * implementation + * Copyright (C) 2019 Shawn Landden + * + * This file is part of Libgcrypt. + * + * Libgcrypt is free software; you can redistribute it and/or modify + * it under the terms of the GNU Lesser general Public License as + * published by the Free Software Foundation; either version 2.1 of + * the License, or (at your option) any later version. + * + * Libgcrypt is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this program; if not, see . + */ + +#include +#include +#include +#include +#include +#include + +#include "g10lib.h" +#include "cipher.h" +#include "bufhelp.h" +#include "./cipher-internal.h" + +#ifdef GCM_USE_PPC_VPMSUM + +#include + +#define ALWAYS_INLINE inline __attribute__((always_inline)) +#define NO_INSTRUMENT_FUNCTION __attribute__((no_instrument_function)) + +#define ASM_FUNC_ATTR NO_INSTRUMENT_FUNCTION +#define ASM_FUNC_ATTR_INLINE ASM_FUNC_ATTR ALWAYS_INLINE + +typedef vector unsigned char vector16x_u8; +typedef vector signed char vector16x_s8; +typedef vector unsigned long long vector2x_u64; +typedef vector unsigned __int128 vector1x_u128; +typedef vector unsigned long long block; + +static ASM_FUNC_ATTR_INLINE block +asm_vpmsumd(block a, block b) +{ + block r; + __asm__("vpmsumd %0, %1, %2" + : "=v" (r) + : "v" (a), "v" (b)); + return r; +} + +static ASM_FUNC_ATTR_INLINE block +asm_swap_u64(block a) +{ + __asm__("xxswapd %x0, %x1" + : "=wa" (a) + : "wa" (a)); + return a; +} + +static ASM_FUNC_ATTR_INLINE block +asm_rot_block_left(block a) +{ + block zero = {0, 0}; + block mask = {2, 0}; + return __builtin_shuffle(a, zero, mask); +} + +static ASM_FUNC_ATTR_INLINE block +asm_rot_block_right(block a) +{ + block zero = {0, 0}; + block mask = {1, 2}; + return __builtin_shuffle(a, zero, mask); +} + +// vsl is a slightly strange function in the way the shift is passed.... +static ASM_FUNC_ATTR_INLINE block +asm_ashl_128(block a, vector16x_u8 shift) +{ + block r; + __asm__("vsl %0, %1, %2" + : "=v" (r) + : "v" (a), "v" (shift)); + return r; +} + +#define ALIGNED_LOAD(in_ptr) \ + (vec_aligned_ld (0, (const unsigned char *)(in_ptr))) + +static ASM_FUNC_ATTR_INLINE block +vec_aligned_ld(unsigned long offset, const unsigned char *ptr) +{ +#ifndef WORDS_BIGENDIAN + block vec; + __asm__ ("lvx %0,%1,%2\n\t" + : "=v" (vec) + : "r" (offset), "r" ((uintptr_t)ptr) + : "memory", "r0"); + return vec; +#else + return vec_vsx_ld (offset, ptr); +#endif +} + +#define STORE_TABLE(gcm_table, slot, vec) \ + vec_aligned_st (((block)vec), slot * 16, (unsigned char *)(gcm_table)); + + +static ASM_FUNC_ATTR_INLINE void +vec_aligned_st(block vec, unsigned long offset, unsigned char *ptr) +{ +#ifndef WORDS_BIGENDIAN + __asm__ ("stvx %0,%1,%2\n\t" + : + : "v" (vec), "r" (offset), "r" ((uintptr_t)ptr) + : "memory", "r0"); +#else + vec_vsx_st ((vector16x_u8)vec, offset, ptr); +#endif +} + +#define VEC_LOAD_BE(in_ptr, bswap_const) \ + (vec_load_be (0, (const unsigned char *)(in_ptr), bswap_const)) + +static ASM_FUNC_ATTR_INLINE block +vec_load_be(unsigned long offset, const unsigned char *ptr, + vector unsigned char be_bswap_const) +{ +#ifndef WORDS_BIGENDIAN + block vec; + /* GCC vec_vsx_ld is generating two instructions on little-endian. Use + * lxvw4x directly instead. */ + __asm__ ("lxvw4x %x0,%1,%2\n\t" + : "=wa" (vec) + : "r" (offset), "r" ((uintptr_t)ptr) + : "memory", "r0"); + __asm__ ("vperm %0,%1,%1,%2\n\t" + : "=v" (vec) + : "v" (vec), "v" (be_bswap_const)); + return vec; +#else + (void)be_bswap_const; + return vec_vsx_ld (offset, ptr); +#endif +} + +/* + Power ghash based on papers: + "The Galois/Counter Mode of Operation (GCM)"; David A. McGrew, John Viega + "Intel® Carry-Less Multiplication Instruction and its Usage for Computing the + GCM Mode - Rev 2.01"; Shay Gueron, Michael E. Kounavis. + + After saving the magic c2 constant and pre-formatted version of the key, + we pre-process the key for parallel hashing. This takes advantage of the identity + of addition over a glois field being identital to XOR, and thus cumulative. (S 2.2, page 3) + We multiply and add (glois field versions) the key over multiple iterations and save the result. + This can later be glois added (XORed) with parallel processed input. + + The ghash "key" is a salt. + */ +void ASM_FUNC_ATTR +_gcry_ghash_setup_ppc_vpmsum (uint64_t *gcm_table, void *gcm_key) +{ + vector16x_u8 bswap_const = { 12, 13, 14, 15, 8, 9, 10, 11, 4, 5, 6, 7, 0, 1, 2, 3 }; + vector16x_u8 c2 = { 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0b11000010}; + block T0, T1, T2; + block C2, H, H1, H1l, H1h, H2, H2l, H2h; + block H3l, H3, H3h, H4l, H4, H4h, T3, T4; + vector16x_s8 most_sig_of_H, t7, carry; + vector16x_u8 one = { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}; + + H = VEC_LOAD_BE(gcm_key, bswap_const); + most_sig_of_H = vec_splat((vector16x_s8)H, 15); + t7 = vec_splat_s8(7); + carry = most_sig_of_H >> t7; + carry &= c2; // only interested in certain carries. + H1 = asm_ashl_128(H, one); + H1 ^= (block)carry; // complete the <<< 1 + + T1 = asm_swap_u64(H1); + H1l = asm_rot_block_right(T1); + H1h = asm_rot_block_left(T1); + C2 = asm_rot_block_right((block)c2); + + STORE_TABLE(gcm_table, 0, C2); + STORE_TABLE(gcm_table, 1, H1l); + STORE_TABLE(gcm_table, 2, T1); + STORE_TABLE(gcm_table, 3, H1h); + + H2l = asm_vpmsumd(H1l, H1); // do not need to mask in because 0 * anything -> 0 + H2 = asm_vpmsumd(T1, H1); + H2h = asm_vpmsumd(H1h, H1); + + // reduce 1 + T0 = asm_vpmsumd(H2l, C2); + + H2l ^= asm_rot_block_left(H2);; + H2h ^= asm_rot_block_right(H2); + H2l = asm_swap_u64(H2l); + H2l ^= T0; + // reduce 2 + T0 = asm_swap_u64(H2l); + H2l = asm_vpmsumd(H2l, C2); + H2 = H2l ^ H2h ^ T0; + + T2 = asm_swap_u64(H2); + H2l = asm_rot_block_right(T2); + H2h = asm_rot_block_left(T2); + + STORE_TABLE(gcm_table, 4, H2l); + STORE_TABLE(gcm_table, 5, T2); + STORE_TABLE(gcm_table, 6, H2h); + + H3l = asm_vpmsumd(H2l, H1); + H4l = asm_vpmsumd(H2l, H2); + H3 = asm_vpmsumd(T2, H1); + H4 = asm_vpmsumd(T2, H2); + H3h = asm_vpmsumd(H2h, H1); + H4h = asm_vpmsumd(H2h, H2); + + T3 = asm_vpmsumd(H3l, C2); + T4 = asm_vpmsumd(H4l, C2); + + H3l ^= asm_rot_block_left(H3); + H3h ^= asm_rot_block_right(H3); + H4l ^= asm_rot_block_left(H4); + H4h ^= asm_rot_block_right(H4); + + H3 = asm_swap_u64(H3l); + H4 = asm_swap_u64(H4l); + + H3 ^= T3; + H4 ^= T4; + + // We could have also b64 switched reduce and reduce2, however as we are + // using the unrotated H and H2 above to vpmsum, this is marginally better. + T3 = asm_swap_u64(H3); + T4 = asm_swap_u64(H4); + + H3 = asm_vpmsumd(H3, C2); + H4 = asm_vpmsumd(H4, C2); + + T3 ^= H3h; + T4 ^= H4h; + H3 ^= T3; + H4 ^= T4; + H3 = asm_swap_u64(H3); + H4 = asm_swap_u64(H4); + + H3l = asm_rot_block_right(H3); + H3h = asm_rot_block_left(H3); + H4l = asm_rot_block_right(H4); + H4h = asm_rot_block_left(H4); + + STORE_TABLE(gcm_table, 7, H3l); + STORE_TABLE(gcm_table, 8, H3); + STORE_TABLE(gcm_table, 9, H3h); + STORE_TABLE(gcm_table, 10, H4l); + STORE_TABLE(gcm_table, 11, H4); + STORE_TABLE(gcm_table, 12, H4h); +} + +ASM_FUNC_ATTR_INLINE +block +vec_perm2(block l, block r, vector16x_u8 perm) { + block ret; + __asm__ ("vperm %0,%1,%2,%3\n\t" + : "=v" (ret) + : "v" (l), "v" (r), "v" (perm)); + return ret; +} + +#include +void ASM_FUNC_ATTR +_gcry_ghash_ppc_vpmsum (const byte *result, const void *const gcm_table, const byte *const buf, + const size_t nblocks) +{ + // This const is strange, it is reversing the bytes, and also reversing the u32s that get switched by lxvw4 + // and it also addresses bytes big-endian, and is here due to lack of proper peep-hole optimization. + vector16x_u8 bswap_const = { 12, 13, 14, 15, 8, 9, 10, 11, 4, 5, 6, 7, 0, 1, 2, 3 }; + vector16x_u8 bswap_8_const = { 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 }; + block c2, H0l, H0m, H0h, H4l, H4m, H4h, H2l, H2m, H2h, H3l, H3m, H3h, Hl, Hm, Hh, in, in0, in1, in2, in3, Hm_right, Hl_rotate, cur; + size_t blocks_remaining = nblocks, off = 0; + + block t0; + + cur = vec_load_be(0, result, bswap_const); + + c2 = vec_aligned_ld(0, gcm_table); + H0l = vec_aligned_ld(16, gcm_table); + H0m = vec_aligned_ld(32, gcm_table); + H0h = vec_aligned_ld(48, gcm_table); + +for (size_t not_multiple_of_four = nblocks % 4; not_multiple_of_four; not_multiple_of_four--) { + in = vec_load_be(off, buf, bswap_const); + off += 16; + blocks_remaining--; + cur ^= in; + + Hl = asm_vpmsumd(cur, H0l); + Hm = asm_vpmsumd(cur, H0m); + Hh = asm_vpmsumd(cur, H0h); + + t0 = asm_vpmsumd(Hl, c2); + + Hl ^= asm_rot_block_left(Hm); + + Hm_right = asm_rot_block_right(Hm); + Hh ^= Hm_right; + Hl_rotate = asm_swap_u64(Hl); + Hl_rotate ^= t0; + Hl = asm_swap_u64(Hl_rotate); + Hl_rotate = asm_vpmsumd(Hl_rotate, c2); + Hl ^= Hh; + Hl ^= Hl_rotate; + + cur = Hl; +} + + if (blocks_remaining > 0) { + vector16x_u8 hiperm = {0x17, 0x16, 0x15, 0x14, 0x13, 0x12, 0x11, 0x10, 0x7, 0x6, 0x5, 0x4, 0x3, 0x2, 0x1, 0x0}, + loperm = {0x1f, 0x1e, 0x1d, 0x1c, 0x1b, 0x1a, 0x19, 0x18, 0xf, 0xe, 0xd, 0xc, 0xb, 0xa, 0x9, 0x8}; + block Xl, Xm, Xh, Xl1, Xm1, Xh1, Xl2, Xm2, Xh2, Xl3, Xm3, Xh3, Xl_rotate; + block H21l, H21h, merge_l, merge_h; + + H2l = vec_aligned_ld(48 + 16, gcm_table); + H2m = vec_aligned_ld(48 + 32, gcm_table); + H2h = vec_aligned_ld(48 + 48, gcm_table); + H3l = vec_aligned_ld(48 * 2 + 16, gcm_table); + H3m = vec_aligned_ld(48 * 2 + 32, gcm_table); + H3h = vec_aligned_ld(48 * 2 + 48, gcm_table); + H4l = vec_aligned_ld(48 * 3 + 16, gcm_table); + H4m = vec_aligned_ld(48 * 3 + 32, gcm_table); + H4h = vec_aligned_ld(48 * 3 + 48, gcm_table); + + in0 = vec_load_be(off, buf, bswap_const); + in1 = vec_load_be(off + 16, buf, bswap_const); + in2 = vec_load_be(off + 32, buf, bswap_const); + in3 = vec_load_be(off + 48, buf, bswap_const); + blocks_remaining -= 4; + off += 64; + + Xh = in0 ^ cur; + + Xl1 = asm_vpmsumd(in1, H3l); + Xm1 = asm_vpmsumd(in1, H3m); + Xh1 = asm_vpmsumd(in1, H3h); + + H21l = vec_perm2(H2m, H0m, hiperm); + H21h = vec_perm2(H2m, H0m, loperm); + merge_l = vec_perm2(in2, in3, loperm); + merge_h = vec_perm2(in2, in3, hiperm); + + Xm2 = asm_vpmsumd(in2, H2m); + Xl3 = asm_vpmsumd(merge_l, H21l); + Xm3 = asm_vpmsumd(in3, H0m); + Xh3 = asm_vpmsumd(merge_h, H21h); + + Xm2 ^= Xm1; + Xl3 ^= Xl1; + Xm3 ^= Xm2; + Xh3 ^= Xh1; + + for (;blocks_remaining > 0; blocks_remaining -= 4, off += 64) { + in0 = vec_load_be(off, buf, bswap_const); + in1 = vec_load_be(off + 16, buf, bswap_const); + in2 = vec_load_be(off + 32, buf, bswap_const); + in3 = vec_load_be(off + 48, buf, bswap_const); + + Xl = asm_vpmsumd(Xh, H4l); + Xm = asm_vpmsumd(Xh, H4m); + Xh = asm_vpmsumd(Xh, H4h); + Xl1 = asm_vpmsumd(in1, H3l); + Xm1 = asm_vpmsumd(in1, H3m); + Xh1 = asm_vpmsumd(in1, H3h); + + Xl ^= Xl3; + Xm ^= Xm3; + Xh ^= Xh3; + merge_l = vec_perm2(in2, in3, loperm); + merge_h = vec_perm2(in2, in3, hiperm); + + t0 = asm_vpmsumd(Xl, c2); + Xl3 = asm_vpmsumd(merge_l, H21l); + Xh3 = asm_vpmsumd(merge_h, H21h); + + Xl ^= asm_rot_block_left(Xm); + Xh ^= asm_rot_block_right(Xm); + + Xl = asm_swap_u64(Xl); + Xl ^= t0; + + Xl_rotate = asm_swap_u64(Xl); + Xm2 = asm_vpmsumd(in2, H2m); + Xm3 = asm_vpmsumd(in3, H0m); + Xl = asm_vpmsumd(Xl, c2); + + Xl3 ^= Xl1; + Xh3 ^= Xh1; + Xh ^= in0; + Xm2 ^= Xm1; + Xh ^= Xl_rotate; + Xm3 ^= Xm2; + Xh ^= Xl; + } + + Xl = asm_vpmsumd(Xh, H4l); + Xm = asm_vpmsumd(Xh, H4m); + Xh = asm_vpmsumd(Xh, H4h); + + Xl ^= Xl3; + Xm ^= Xm3; + + t0 = asm_vpmsumd(Xl, c2); + + Xh ^= Xh3; + Xl ^= asm_rot_block_left(Xm); + Xh ^= asm_rot_block_right(Xm); + + Xl = asm_swap_u64(Xl); + Xl ^= t0; + + Xl_rotate = asm_swap_u64(Xl); + Xl = asm_vpmsumd(Xl, c2); + Xl_rotate ^= Xh; + Xl ^= Xl_rotate; + + cur = Xl; + } + cur = (block)vec_perm((vector16x_u8)cur, (vector16x_u8)cur, bswap_8_const); + STORE_TABLE(result, 0, cur); +} + +#endif /* GCM_USE_PPC_VPMSUM */ Index: cipher/cipher-gcm.c =================================================================== --- cipher/cipher-gcm.c +++ cipher/cipher-gcm.c @@ -89,6 +89,29 @@ } #endif /* GCM_USE_ARM_NEON */ +#ifdef GCM_USE_PPC_VPMSUM +extern void _gcry_ghash_setup_ppc_vpmsum (void *gcm_table, void *gcm_key); + +/* result is 128-bits */ +extern unsigned int _gcry_ghash_ppc_vpmsum (byte *result, void *gcm_table, + const byte *buf, size_t nblocks); + +static void +ghash_setup_ppc_vpmsum (gcry_cipher_hd_t c) +{ + _gcry_ghash_setup_ppc_vpmsum(c->u_mode.gcm.gcm_table, c->u_mode.gcm.u_ghash_key.key); +} + +static unsigned int +ghash_ppc_vpmsum (gcry_cipher_hd_t c, byte *result, const byte *buf, + size_t nblocks) +{ + unsigned __int128 *where = (unsigned __int128*)result; + _gcry_ghash_ppc_vpmsum(result, c->u_mode.gcm.gcm_table, buf, + nblocks); + return 0; +} +#endif /* GCM_USE_PPC_VPMSUM */ #ifdef GCM_USE_TABLES static struct @@ -522,7 +545,7 @@ static void setupM (gcry_cipher_hd_t c) { -#if defined(GCM_USE_INTEL_PCLMUL) || defined(GCM_USE_ARM_PMULL) +#if defined(GCM_USE_INTEL_PCLMUL) || defined(GCM_USE_ARM_PMULL) || defined(GCM_USE_PPC_VPMSUM) unsigned int features = _gcry_get_hw_features (); #endif @@ -548,6 +571,13 @@ c->u_mode.gcm.ghash_fn = ghash_armv7_neon; ghash_setup_armv7_neon (c); } +#endif +#ifdef GCM_USE_PPC_VPMSUM + else if (features & HWF_PPC_VCRYPTO) + { + c->u_mode.gcm.ghash_fn = ghash_ppc_vpmsum; + ghash_setup_ppc_vpmsum (c); + } #endif else { Index: cipher/cipher-internal.h =================================================================== --- cipher/cipher-internal.h +++ cipher/cipher-internal.h @@ -96,6 +96,18 @@ #endif #endif /* GCM_USE_ARM_NEON */ +/* GCM_USE_PPC_VPMSUM indicates whether to compile GCM with PPC Power 8 polynomial multiplication instruction */ +#undef GCM_USE_PPC_VPMSUM +#if defined(GCM_USE_TABLES) +#if defined(ENABLE_PPC_CRYPTO_SUPPORT) && defined(__powerpc64__) && defined(__LITTLE_ENDIAN__) && \ + defined(HAVE_COMPATIBLE_CC_PPC_ALTIVEC) && \ + defined(HAVE_GCC_INLINE_ASM_PPC_ALTIVEC) && \ + __GNUC__ >= 4 +# define GCM_USE_PPC_VPMSUM 1 +# define NEED_16BYTE_ALIGNED_CONTEXT 1 /* this also aligns gcm_table */ +#endif +#endif /* GCM_USE_PPC_VPMSUM */ + typedef unsigned int (*ghash_fn_t) (gcry_cipher_hd_t c, byte *result, const byte *buf, size_t nblocks); @@ -309,9 +321,6 @@ unsigned char key[MAX_BLOCKSIZE]; } u_ghash_key; - /* GHASH implementation in use. */ - ghash_fn_t ghash_fn; - /* Pre-calculated table for GCM. */ #ifdef GCM_USE_TABLES #if (SIZEOF_UNSIGNED_LONG == 8 || defined(__x86_64__)) @@ -322,6 +331,9 @@ u32 gcm_table[8 * 16]; #endif #endif + + /* GHASH implementation in use. */ + ghash_fn_t ghash_fn; } gcm; /* Mode specific storage for OCB mode. */ Index: tests/basic.c =================================================================== --- tests/basic.c +++ tests/basic.c @@ -3135,6 +3135,22 @@ "\x0f\xc0\xc3\xb7\x80\xf2\x44\x45\x2d\xa3\xeb\xf1\xc5\xd8\x2c\xde" "\xa2\x41\x89\x97\x20\x0e\xf8\x2e\x44\xae\x7e\x3f", "\xa4\x4a\x82\x66\xee\x1c\x8e\xb0\xc8\xb5\xd4\xcf\x5a\xe9\xf1\x9a" }, + { GCRY_CIPHER_AES256, + "\xfe\xff\xe9\x92\x86\x65\x73\x1c\x6d\x6a\x8f\x94\x67\x30\x83\x08" + "\xfe\xff\xe9\x92\x86\x65\x73\x1c\x6d\x6a\x8f\x94\x67\x30\x83\x08", + "\xca\xfe\xba\xbe\xfa\xce\xdb\xad\xde\xca\xf8\x88", 12, + "\xfe\xed\xfa\xce\xde\xad\xbe\xef\xfe\xed\xfa\xce\xde\xad\xbe\xef" + "\xab\xad\xda\xd2", 20, + "\xd9\x31\x32\x25\xf8\x84\x06\xe5\xa5\x59\x09\xc5\xaf\xf5\x26\x9a" + "\x86\xa7\xa9\x53\x15\x34\xf7\xda\x2e\x4c\x30\x3d\x8a\x31\x8a\x72" + "\x1c\x3c\x0c\x95\x95\x68\x09\x53\x2f\xcf\x0e\x24\x49\xa6\xb5\x25" + "\xb1\x6a\xed\xf5\xaa\x0d\xe6\x57\xba\x63\x7b\x39", + 60, + "\x52\x2d\xc1\xf0\x99\x56\x7d\x07\xf4\x7f\x37\xa3\x2a\x84\x42\x7d" + "\x64\x3a\x8c\xdc\xbf\xe5\xc0\xc9\x75\x98\xa2\xbd\x25\x55\xd1\xaa" + "\x8c\xb0\x8e\x48\x59\x0d\xbb\x3d\xa7\xb0\x8b\x10\x56\x82\x88\x38" + "\xc5\xf6\x1e\x63\x93\xba\x7a\x0a\xbc\xc9\xf6\x62", + "\x76\xfc\x6e\xce\x0f\x4e\x17\x68\xcd\xdf\x88\x53\xbb\x2d\x55\x1b" }, /* Test vectors for overflowing CTR. */ /* After setiv, ctr_low: 0xffffffff */ { GCRY_CIPHER_AES256,