From mboxrd@z Thu Jan 1 00:00:00 1970 From: AKASHI Takahiro Date: Tue, 14 Jan 2020 16:15:16 +0900 Subject: [PATCH v4 4/6] lib: rsa: generate additional parameters for public key In-Reply-To: References: <20191121001121.21854-1-takahiro.akashi@linaro.org> <20191121001121.21854-5-takahiro.akashi@linaro.org> Message-ID: <20200114071515.GD28530@linaro.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Wed, Jan 08, 2020 at 07:07:01PM +0100, Heinrich Schuchardt wrote: > > > On 11/21/19 1:11 AM, AKASHI Takahiro wrote: > >In the current implementation of FIT_SIGNATURE, five parameters for > >a RSA public key are required while only two of them are essential. > >(See rsa-mod-exp.h and uImage.FIT/signature.txt) > >This is a result of considering relatively limited computer power > >and resources on embedded systems, while such a assumption may not > >be quite practical for other use cases. > > > >In this patch, added is a function, rsa_gen_key_prop(), which will > >generate additional parameters for other uses, in particular > >UEFI secure boot, on the fly. > > > >Note: the current code uses some "big number" rouKtines from BearSSL > >for the calculation. > > > >Signed-off-by: AKASHI Takahiro > >--- > > include/u-boot/rsa-mod-exp.h | 23 ++ > > lib/rsa/Kconfig | 1 + > > lib/rsa/Makefile | 1 + > > lib/rsa/rsa-keyprop.c | 725 +++++++++++++++++++++++++++++++++++ > > 4 files changed, 750 insertions(+) > > create mode 100644 lib/rsa/rsa-keyprop.c > > > >diff --git a/include/u-boot/rsa-mod-exp.h b/include/u-boot/rsa-mod-exp.h > >index 8a428c4b6a1a..1da8af1bb83d 100644 > >--- a/include/u-boot/rsa-mod-exp.h > >+++ b/include/u-boot/rsa-mod-exp.h > >@@ -26,6 +26,29 @@ struct key_prop { > > uint32_t exp_len; /* Exponent length in number of uint8_t */ > > }; > > > >+/** > >+ * rsa_gen_key_prop() - Generate key properties of RSA public key > >+ * @key: Specifies key data in DER format > >+ * @keylen: Length of @key > >+ * @prop: Generated key property > >+ * > >+ * This function takes a blob of encoded RSA public key data in DER > >+ * format, parse it and generate all the relevant properties > >+ * in key_prop structure. > >+ * Return a pointer to struct key_prop in @prop on success. > >+ * > >+ * Return: 0 on success, negative on error > >+ */ > >+int rsa_gen_key_prop(const void *key, uint32_t keylen, struct key_prop **proc); > >+ > >+/** > >+ * rsa_free_key_prop() - Free key properties > >+ * @prop: Pointer to struct key_prop > >+ * > >+ * This function frees all the memories allocated by rsa_gen_key_prop(). > >+ */ > >+void rsa_free_key_prop(struct key_prop *prop); > >+ > > /** > > * rsa_mod_exp_sw() - Perform RSA Modular Exponentiation in sw > > * > >diff --git a/lib/rsa/Kconfig b/lib/rsa/Kconfig > >index 71e4c06bf883..d1d6f6cf64a3 100644 > >--- a/lib/rsa/Kconfig > >+++ b/lib/rsa/Kconfig > >@@ -33,6 +33,7 @@ config RSA_VERIFY > > config RSA_VERIFY_WITH_PKEY > > bool "Execute RSA verification without key parameters from FDT" > > depends on RSA > >+ imply RSA_PUBLIC_KEY_PARSER > > Do we really need RSA_PUBLIC_KEY_PARSER whenever we use CONFIG_RSA=y? ??? RSA_PUBLIC_KEY_PARSER will be selected only if RSA_VERIFY_WITH_PKEY is enabled. I avoided to use 'select' here because RSA_PUBLIC_KEY_PARSER is also 'selectable.' > E.g. on a system without the UEFI sub-system? > > Otherwise simply let RSA_PUBLIC_KEY_PARSER depend on RSA. Such a dependency sounds odd to me. > > > help > > The standard RSA-signature verification code (FIT_SIGNATURE) uses > > pre-calculated key properties, that are stored in fdt blob, in > >diff --git a/lib/rsa/Makefile b/lib/rsa/Makefile > >index c07305188e0c..14ed3cb4012b 100644 > >--- a/lib/rsa/Makefile > >+++ b/lib/rsa/Makefile > >@@ -6,4 +6,5 @@ > > # Wolfgang Denk, DENX Software Engineering, wd at denx.de. > > > > obj-$(CONFIG_$(SPL_)RSA_VERIFY) += rsa-verify.o rsa-checksum.o > >+obj-$(CONFIG_RSA_VERIFY_WITH_PKEY) += rsa-keyprop.o > > obj-$(CONFIG_RSA_SOFTWARE_EXP) += rsa-mod-exp.o > >diff --git a/lib/rsa/rsa-keyprop.c b/lib/rsa/rsa-keyprop.c > >new file mode 100644 > >index 000000000000..9464df009343 > >--- /dev/null > >+++ b/lib/rsa/rsa-keyprop.c > >@@ -0,0 +1,725 @@ > >+// SPDX-License-Identifier: GPL-2.0+ and MIT > >+/* > >+ * RSA library - generate parameters for a public key > >+ * > >+ * Copyright (c) 2019 Linaro Limited > >+ * Author: AKASHI Takahiro > >+ * > >+ * Big number routines in this file come from BearSSL: > >+ * Copyright (c) 2016 Thomas Pornin > >+ */ > >+ > >+#include > >+#include > >+#include > >+#include > >+#include > >+#include > >+ > >+/** > >+ * br_dec16be() - Convert 16-bit big-endian integer to native > >+ * @src: Pointer to data > >+ * Return: Native-endian integer > >+ */ > >+static unsigned br_dec16be(const void *src) > >+{ > >+ return be16_to_cpup(src); > >+} > >+ > >+/** > >+ * br_dec32be() - Convert 32-bit big-endian integer to native > >+ * @src: Pointer to data > >+ * Return: Native-endian integer > >+ */ > >+static uint32_t br_dec32be(const void *src) > >+{ > >+ return be32_to_cpup(src); > >+} > >+ > >+/** > >+ * br_enc32be() - Convert native 32-bit integer to big-endian > >+ * @dst: Pointer to buffer to store big-endian integer in > >+ * @x: Native 32-bit integer > >+ */ > >+static void br_enc32be(void *dst, uint32_t x) > >+{ > >+ __be32 tmp; > >+ > >+ tmp = cpu_to_be32(x); > >+ memcpy(dst, &tmp, sizeof(tmp)); > >+} > >+ > >+/* from BearSSL's src/inner.h */ > >+ > >+/* > >+ * Negate a boolean. > >+ */ > >+static uint32_t NOT(uint32_t ctl) > >+{ > >+ return ctl ^ 1; > >+} > >+ > >+/* > >+ * Multiplexer: returns x if ctl == 1, y if ctl == 0. > >+ */ > >+static uint32_t MUX(uint32_t ctl, uint32_t x, uint32_t y) > >+{ > >+ return y ^ (-ctl & (x ^ y)); > >+} > >+ > >+/* > >+ * Equality check: returns 1 if x == y, 0 otherwise. > >+ */ > >+static uint32_t EQ(uint32_t x, uint32_t y) > >+{ > >+ uint32_t q; > >+ > >+ q = x ^ y; > >+ return NOT((q | -q) >> 31); > >+} > >+ > >+/* > >+ * Inequality check: returns 1 if x != y, 0 otherwise. > >+ */ > >+static uint32_t NEQ(uint32_t x, uint32_t y) > >+{ > >+ uint32_t q; > >+ > >+ q = x ^ y; > >+ return (q | -q) >> 31; > > We want to minimize the code size of U-Boot. I don't get your point. Please elaborate your concern. > So, please, review this code and remove all of this bogus. Which part of the code do you mention as 'bogus'? Thanks, -Takahiro Akashi > > Best regards > > Heinrich > > >+} > >+ > >+/* > >+ * Comparison: returns 1 if x > y, 0 otherwise. > >+ */ > >+static uint32_t GT(uint32_t x, uint32_t y) > >+{ > >+ /* > >+ * If both x < 2^31 and y < 2^31, then y-x will have its high > >+ * bit set if x > y, cleared otherwise. > >+ * > >+ * If either x >= 2^31 or y >= 2^31 (but not both), then the > >+ * result is the high bit of x. > >+ * > >+ * If both x >= 2^31 and y >= 2^31, then we can virtually > >+ * subtract 2^31 from both, and we are back to the first case. > >+ * Since (y-2^31)-(x-2^31) = y-x, the subtraction is already > >+ * fine. > >+ */ > >+ uint32_t z; > >+ > >+ z = y - x; > >+ return (z ^ ((x ^ y) & (x ^ z))) >> 31; > >+} > >+ > >+/* > >+ * Compute the bit length of a 32-bit integer. Returned value is between 0 > >+ * and 32 (inclusive). > >+ */ > >+static uint32_t BIT_LENGTH(uint32_t x) > >+{ > >+ uint32_t k, c; > >+ > >+ k = NEQ(x, 0); > >+ c = GT(x, 0xFFFF); x = MUX(c, x >> 16, x); k += c << 4; > >+ c = GT(x, 0x00FF); x = MUX(c, x >> 8, x); k += c << 3; > >+ c = GT(x, 0x000F); x = MUX(c, x >> 4, x); k += c << 2; > >+ c = GT(x, 0x0003); x = MUX(c, x >> 2, x); k += c << 1; > >+ k += GT(x, 0x0001); > >+ return k; > >+} > >+ > >+#define GE(x, y) NOT(GT(y, x)) > >+#define LT(x, y) GT(y, x) > >+#define MUL(x, y) ((uint64_t)(x) * (uint64_t)(y)) > >+ > >+/* > >+ * Integers 'i32' > >+ * -------------- > >+ * > >+ * The 'i32' functions implement computations on big integers using > >+ * an internal representation as an array of 32-bit integers. For > >+ * an array x[]: > >+ * -- x[0] contains the "announced bit length" of the integer > >+ * -- x[1], x[2]... contain the value in little-endian order (x[1] > >+ * contains the least significant 32 bits) > >+ * > >+ * Multiplications rely on the elementary 32x32->64 multiplication. > >+ * > >+ * The announced bit length specifies the number of bits that are > >+ * significant in the subsequent 32-bit words. Unused bits in the > >+ * last (most significant) word are set to 0; subsequent words are > >+ * uninitialized and need not exist at all. > >+ * > >+ * The execution time and memory access patterns of all computations > >+ * depend on the announced bit length, but not on the actual word > >+ * values. For modular integers, the announced bit length of any integer > >+ * modulo n is equal to the actual bit length of n; thus, computations > >+ * on modular integers are "constant-time" (only the modulus length may > >+ * leak). > >+ */ > >+ > >+/* > >+ * Extract one word from an integer. The offset is counted in bits. > >+ * The word MUST entirely fit within the word elements corresponding > >+ * to the announced bit length of a[]. > >+ */ > >+static uint32_t br_i32_word(const uint32_t *a, uint32_t off) > >+{ > >+ size_t u; > >+ unsigned j; > >+ > >+ u = (size_t)(off >> 5) + 1; > >+ j = (unsigned)off & 31; > >+ if (j == 0) { > >+ return a[u]; > >+ } else { > >+ return (a[u] >> j) | (a[u + 1] << (32 - j)); > >+ } > >+} > >+ > >+/* from BearSSL's src/int/i32_bitlen.c */ > >+ > >+/* > >+ * Compute the actual bit length of an integer. The argument x should > >+ * point to the first (least significant) value word of the integer. > >+ * The len 'xlen' contains the number of 32-bit words to access. > >+ * > >+ * CT: value or length of x does not leak. > >+ */ > >+static uint32_t br_i32_bit_length(uint32_t *x, size_t xlen) > >+{ > >+ uint32_t tw, twk; > >+ > >+ tw = 0; > >+ twk = 0; > >+ while (xlen -- > 0) { > >+ uint32_t w, c; > >+ > >+ c = EQ(tw, 0); > >+ w = x[xlen]; > >+ tw = MUX(c, w, tw); > >+ twk = MUX(c, (uint32_t)xlen, twk); > >+ } > >+ return (twk << 5) + BIT_LENGTH(tw); > >+} > >+ > >+/* from BearSSL's src/int/i32_decode.c */ > >+ > >+/* > >+ * Decode an integer from its big-endian unsigned representation. The > >+ * "true" bit length of the integer is computed, but all words of x[] > >+ * corresponding to the full 'len' bytes of the source are set. > >+ * > >+ * CT: value or length of x does not leak. > >+ */ > >+static void br_i32_decode(uint32_t *x, const void *src, size_t len) > >+{ > >+ const unsigned char *buf; > >+ size_t u, v; > >+ > >+ buf = src; > >+ u = len; > >+ v = 1; > >+ for (;;) { > >+ if (u < 4) { > >+ uint32_t w; > >+ > >+ if (u < 2) { > >+ if (u == 0) { > >+ break; > >+ } else { > >+ w = buf[0]; > >+ } > >+ } else { > >+ if (u == 2) { > >+ w = br_dec16be(buf); > >+ } else { > >+ w = ((uint32_t)buf[0] << 16) > >+ | br_dec16be(buf + 1); > >+ } > >+ } > >+ x[v ++] = w; > >+ break; > >+ } else { > >+ u -= 4; > >+ x[v ++] = br_dec32be(buf + u); > >+ } > >+ } > >+ x[0] = br_i32_bit_length(x + 1, v - 1); > >+} > >+ > >+/* from BearSSL's src/int/i32_encode.c */ > >+ > >+/* > >+ * Encode an integer into its big-endian unsigned representation. The > >+ * output length in bytes is provided (parameter 'len'); if the length > >+ * is too short then the integer is appropriately truncated; if it is > >+ * too long then the extra bytes are set to 0. > >+ */ > >+static void br_i32_encode(void *dst, size_t len, const uint32_t *x) > >+{ > >+ unsigned char *buf; > >+ size_t k; > >+ > >+ buf = dst; > >+ > >+ /* > >+ * Compute the announced size of x in bytes; extra bytes are > >+ * filled with zeros. > >+ */ > >+ k = (x[0] + 7) >> 3; > >+ while (len > k) { > >+ *buf ++ = 0; > >+ len --; > >+ } > >+ > >+ /* > >+ * Now we use k as index within x[]. That index starts at 1; > >+ * we initialize it to the topmost complete word, and process > >+ * any remaining incomplete word. > >+ */ > >+ k = (len + 3) >> 2; > >+ switch (len & 3) { > >+ case 3: > >+ *buf ++ = x[k] >> 16; > >+ /* fall through */ > >+ case 2: > >+ *buf ++ = x[k] >> 8; > >+ /* fall through */ > >+ case 1: > >+ *buf ++ = x[k]; > >+ k --; > >+ } > >+ > >+ /* > >+ * Encode all complete words. > >+ */ > >+ while (k > 0) { > >+ br_enc32be(buf, x[k]); > >+ k --; > >+ buf += 4; > >+ } > >+} > >+ > >+/* from BearSSL's src/int/i32_ninv32.c */ > >+ > >+/* > >+ * Compute -(1/x) mod 2^32. If x is even, then this function returns 0. > >+ */ > >+static uint32_t br_i32_ninv32(uint32_t x) > >+{ > >+ uint32_t y; > >+ > >+ y = 2 - x; > >+ y *= 2 - y * x; > >+ y *= 2 - y * x; > >+ y *= 2 - y * x; > >+ y *= 2 - y * x; > >+ return MUX(x & 1, -y, 0); > >+} > >+ > >+/* from BearSSL's src/int/i32_add.c */ > >+ > >+/* > >+ * Add b[] to a[] and return the carry (0 or 1). If ctl is 0, then a[] > >+ * is unmodified, but the carry is still computed and returned. The > >+ * arrays a[] and b[] MUST have the same announced bit length. > >+ * > >+ * a[] and b[] MAY be the same array, but partial overlap is not allowed. > >+ */ > >+static uint32_t br_i32_add(uint32_t *a, const uint32_t *b, uint32_t ctl) > >+{ > >+ uint32_t cc; > >+ size_t u, m; > >+ > >+ cc = 0; > >+ m = (a[0] + 63) >> 5; > >+ for (u = 1; u < m; u ++) { > >+ uint32_t aw, bw, naw; > >+ > >+ aw = a[u]; > >+ bw = b[u]; > >+ naw = aw + bw + cc; > >+ > >+ /* > >+ * Carry is 1 if naw < aw. Carry is also 1 if naw == aw > >+ * AND the carry was already 1. > >+ */ > >+ cc = (cc & EQ(naw, aw)) | LT(naw, aw); > >+ a[u] = MUX(ctl, naw, aw); > >+ } > >+ return cc; > >+} > >+ > >+/* from BearSSL's src/int/i32_sub.c */ > >+ > >+/* > >+ * Subtract b[] from a[] and return the carry (0 or 1). If ctl is 0, > >+ * then a[] is unmodified, but the carry is still computed and returned. > >+ * The arrays a[] and b[] MUST have the same announced bit length. > >+ * > >+ * a[] and b[] MAY be the same array, but partial overlap is not allowed. > >+ */ > >+static uint32_t br_i32_sub(uint32_t *a, const uint32_t *b, uint32_t ctl) > >+{ > >+ uint32_t cc; > >+ size_t u, m; > >+ > >+ cc = 0; > >+ m = (a[0] + 63) >> 5; > >+ for (u = 1; u < m; u ++) { > >+ uint32_t aw, bw, naw; > >+ > >+ aw = a[u]; > >+ bw = b[u]; > >+ naw = aw - bw - cc; > >+ > >+ /* > >+ * Carry is 1 if naw > aw. Carry is 1 also if naw == aw > >+ * AND the carry was already 1. > >+ */ > >+ cc = (cc & EQ(naw, aw)) | GT(naw, aw); > >+ a[u] = MUX(ctl, naw, aw); > >+ } > >+ return cc; > >+} > >+ > >+/* from BearSSL's src/int/i32_div32.c */ > >+ > >+/* > >+ * Constant-time division. The dividend hi:lo is divided by the > >+ * divisor d; the quotient is returned and the remainder is written > >+ * in *r. If hi == d, then the quotient does not fit on 32 bits; > >+ * returned value is thus truncated. If hi > d, returned values are > >+ * indeterminate. > >+ */ > >+static uint32_t br_divrem(uint32_t hi, uint32_t lo, uint32_t d, uint32_t *r) > >+{ > >+ /* TODO: optimize this */ > >+ uint32_t q; > >+ uint32_t ch, cf; > >+ int k; > >+ > >+ q = 0; > >+ ch = EQ(hi, d); > >+ hi = MUX(ch, 0, hi); > >+ for (k = 31; k > 0; k --) { > >+ int j; > >+ uint32_t w, ctl, hi2, lo2; > >+ > >+ j = 32 - k; > >+ w = (hi << j) | (lo >> k); > >+ ctl = GE(w, d) | (hi >> k); > >+ hi2 = (w - d) >> j; > >+ lo2 = lo - (d << k); > >+ hi = MUX(ctl, hi2, hi); > >+ lo = MUX(ctl, lo2, lo); > >+ q |= ctl << k; > >+ } > >+ cf = GE(lo, d) | hi; > >+ q |= cf; > >+ *r = MUX(cf, lo - d, lo); > >+ return q; > >+} > >+ > >+/* > >+ * Wrapper for br_divrem(); the remainder is returned, and the quotient > >+ * is discarded. > >+ */ > >+static uint32_t br_rem(uint32_t hi, uint32_t lo, uint32_t d) > >+{ > >+ uint32_t r; > >+ > >+ br_divrem(hi, lo, d, &r); > >+ return r; > >+} > >+ > >+/* > >+ * Wrapper for br_divrem(); the quotient is returned, and the remainder > >+ * is discarded. > >+ */ > >+static uint32_t br_div(uint32_t hi, uint32_t lo, uint32_t d) > >+{ > >+ uint32_t r; > >+ > >+ return br_divrem(hi, lo, d, &r); > >+} > >+ > >+/* from BearSSL's src/int/i32_muladd.c */ > >+ > >+/* > >+ * Multiply x[] by 2^32 and then add integer z, modulo m[]. This > >+ * function assumes that x[] and m[] have the same announced bit > >+ * length, and the announced bit length of m[] matches its true > >+ * bit length. > >+ * > >+ * x[] and m[] MUST be distinct arrays. > >+ * > >+ * CT: only the common announced bit length of x and m leaks, not > >+ * the values of x, z or m. > >+ */ > >+static void br_i32_muladd_small(uint32_t *x, uint32_t z, const uint32_t *m) > >+{ > >+ uint32_t m_bitlen; > >+ size_t u, mlen; > >+ uint32_t a0, a1, b0, hi, g, q, tb; > >+ uint32_t chf, clow, under, over; > >+ uint64_t cc; > >+ > >+ /* > >+ * We can test on the modulus bit length since we accept to > >+ * leak that length. > >+ */ > >+ m_bitlen = m[0]; > >+ if (m_bitlen == 0) { > >+ return; > >+ } > >+ if (m_bitlen <= 32) { > >+ x[1] = br_rem(x[1], z, m[1]); > >+ return; > >+ } > >+ mlen = (m_bitlen + 31) >> 5; > >+ > >+ /* > >+ * Principle: we estimate the quotient (x*2^32+z)/m by > >+ * doing a 64/32 division with the high words. > >+ * > >+ * Let: > >+ * w = 2^32 > >+ * a = (w*a0 + a1) * w^N + a2 > >+ * b = b0 * w^N + b2 > >+ * such that: > >+ * 0 <= a0 < w > >+ * 0 <= a1 < w > >+ * 0 <= a2 < w^N > >+ * w/2 <= b0 < w > >+ * 0 <= b2 < w^N > >+ * a < w*b > >+ * I.e. the two top words of a are a0:a1, the top word of b is > >+ * b0, we ensured that b0 is "full" (high bit set), and a is > >+ * such that the quotient q = a/b fits on one word (0 <= q < w). > >+ * > >+ * If a = b*q + r (with 0 <= r < q), we can estimate q by > >+ * doing an Euclidean division on the top words: > >+ * a0*w+a1 = b0*u + v (with 0 <= v < w) > >+ * Then the following holds: > >+ * 0 <= u <= w > >+ * u-2 <= q <= u > >+ */ > >+ a0 = br_i32_word(x, m_bitlen - 32); > >+ hi = x[mlen]; > >+ memmove(x + 2, x + 1, (mlen - 1) * sizeof *x); > >+ x[1] = z; > >+ a1 = br_i32_word(x, m_bitlen - 32); > >+ b0 = br_i32_word(m, m_bitlen - 32); > >+ > >+ /* > >+ * We estimate a divisor q. If the quotient returned by br_div() > >+ * is g: > >+ * -- If a0 == b0 then g == 0; we want q = 0xFFFFFFFF. > >+ * -- Otherwise: > >+ * -- if g == 0 then we set q = 0; > >+ * -- otherwise, we set q = g - 1. > >+ * The properties described above then ensure that the true > >+ * quotient is q-1, q or q+1. > >+ */ > >+ g = br_div(a0, a1, b0); > >+ q = MUX(EQ(a0, b0), 0xFFFFFFFF, MUX(EQ(g, 0), 0, g - 1)); > >+ > >+ /* > >+ * We subtract q*m from x (with the extra high word of value 'hi'). > >+ * Since q may be off by 1 (in either direction), we may have to > >+ * add or subtract m afterwards. > >+ * > >+ * The 'tb' flag will be true (1) at the end of the loop if the > >+ * result is greater than or equal to the modulus (not counting > >+ * 'hi' or the carry). > >+ */ > >+ cc = 0; > >+ tb = 1; > >+ for (u = 1; u <= mlen; u ++) { > >+ uint32_t mw, zw, xw, nxw; > >+ uint64_t zl; > >+ > >+ mw = m[u]; > >+ zl = MUL(mw, q) + cc; > >+ cc = (uint32_t)(zl >> 32); > >+ zw = (uint32_t)zl; > >+ xw = x[u]; > >+ nxw = xw - zw; > >+ cc += (uint64_t)GT(nxw, xw); > >+ x[u] = nxw; > >+ tb = MUX(EQ(nxw, mw), tb, GT(nxw, mw)); > >+ } > >+ > >+ /* > >+ * If we underestimated q, then either cc < hi (one extra bit > >+ * beyond the top array word), or cc == hi and tb is true (no > >+ * extra bit, but the result is not lower than the modulus). In > >+ * these cases we must subtract m once. > >+ * > >+ * Otherwise, we may have overestimated, which will show as > >+ * cc > hi (thus a negative result). Correction is adding m once. > >+ */ > >+ chf = (uint32_t)(cc >> 32); > >+ clow = (uint32_t)cc; > >+ over = chf | GT(clow, hi); > >+ under = ~over & (tb | (~chf & LT(clow, hi))); > >+ br_i32_add(x, m, over); > >+ br_i32_sub(x, m, under); > >+} > >+ > >+/* from BearSSL's src/int/i32_reduce.c */ > >+ > >+/* > >+ * Reduce an integer (a[]) modulo another (m[]). The result is written > >+ * in x[] and its announced bit length is set to be equal to that of m[]. > >+ * > >+ * x[] MUST be distinct from a[] and m[]. > >+ * > >+ * CT: only announced bit lengths leak, not values of x, a or m. > >+ */ > >+static void br_i32_reduce(uint32_t *x, const uint32_t *a, const uint32_t *m) > >+{ > >+ uint32_t m_bitlen, a_bitlen; > >+ size_t mlen, alen, u; > >+ > >+ m_bitlen = m[0]; > >+ mlen = (m_bitlen + 31) >> 5; > >+ > >+ x[0] = m_bitlen; > >+ if (m_bitlen == 0) { > >+ return; > >+ } > >+ > >+ /* > >+ * If the source is shorter, then simply copy all words from a[] > >+ * and zero out the upper words. > >+ */ > >+ a_bitlen = a[0]; > >+ alen = (a_bitlen + 31) >> 5; > >+ if (a_bitlen < m_bitlen) { > >+ memcpy(x + 1, a + 1, alen * sizeof *a); > >+ for (u = alen; u < mlen; u ++) { > >+ x[u + 1] = 0; > >+ } > >+ return; > >+ } > >+ > >+ /* > >+ * The source length is at least equal to that of the modulus. > >+ * We must thus copy N-1 words, and input the remaining words > >+ * one by one. > >+ */ > >+ memcpy(x + 1, a + 2 + (alen - mlen), (mlen - 1) * sizeof *a); > >+ x[mlen] = 0; > >+ for (u = 1 + alen - mlen; u > 0; u --) { > >+ br_i32_muladd_small(x, a[u], m); > >+ } > >+} > >+ > >+/** > >+ * rsa_free_key_prop() - Free key properties > >+ * @prop: Pointer to struct key_prop > >+ * > >+ * This function frees all the memories allocated by rsa_gen_key_prop(). > >+ */ > >+void rsa_free_key_prop(struct key_prop *prop) > >+{ > >+ if (!prop) > >+ return; > >+ > >+ free((void *)prop->modulus); > >+ free((void *)prop->public_exponent); > >+ free((void *)prop->rr); > >+ > >+ free(prop); > >+} > >+ > >+/** > >+ * rsa_gen_key_prop() - Generate key properties of RSA public key > >+ * @key: Specifies key data in DER format > >+ * @keylen: Length of @key > >+ * @prop: Generated key property > >+ * > >+ * This function takes a blob of encoded RSA public key data in DER > >+ * format, parse it and generate all the relevant properties > >+ * in key_prop structure. > >+ * Return a pointer to struct key_prop in @prop on success. > >+ * > >+ * Return: 0 on success, negative on error > >+ */ > >+int rsa_gen_key_prop(const void *key, uint32_t keylen, struct key_prop **prop) > >+{ > >+ struct rsa_key rsa_key; > >+ uint32_t *n = NULL, *rr = NULL, *rrtmp = NULL; > >+ const int max_rsa_size = 4096; > >+ int rlen, i, ret; > >+ > >+ *prop = calloc(sizeof(**prop), 1); > >+ n = calloc(sizeof(uint32_t), 1 + (max_rsa_size >> 5)); > >+ rr = calloc(sizeof(uint32_t), 1 + (max_rsa_size >> 5)); > >+ rrtmp = calloc(sizeof(uint32_t), 1 + (max_rsa_size >> 5)); > >+ if (!(*prop) || !n || !rr || !rrtmp) { > >+ ret = -ENOMEM; > >+ goto err; > >+ } > >+ > >+ ret = rsa_parse_pub_key(&rsa_key, key, keylen); > >+ if (ret) > >+ goto err; > >+ > >+ /* modulus */ > >+ /* removing leading 0's */ > >+ for (i = 0; i < rsa_key.n_sz && !rsa_key.n[i]; i++) > >+ ; > >+ (*prop)->num_bits = (rsa_key.n_sz - i) * 8; > >+ (*prop)->modulus = malloc(rsa_key.n_sz - i); > >+ if (!(*prop)->modulus) { > >+ ret = -ENOMEM; > >+ goto err; > >+ } > >+ memcpy((void *)(*prop)->modulus, &rsa_key.n[i], rsa_key.n_sz - i); > >+ > >+ /* exponent */ > >+ (*prop)->public_exponent = calloc(1, sizeof(uint64_t)); > >+ if (!(*prop)->public_exponent) { > >+ ret = -ENOMEM; > >+ goto err; > >+ } > >+ memcpy((void *)(*prop)->public_exponent + sizeof(uint64_t) > >+ - rsa_key.e_sz, > >+ rsa_key.e, rsa_key.e_sz); > >+ (*prop)->exp_len = rsa_key.e_sz; > >+ > >+ /* n0 inverse */ > >+ br_i32_decode(n, &rsa_key.n[i], rsa_key.n_sz - i); > >+ (*prop)->n0inv = br_i32_ninv32(n[1]); > >+ > >+ /* R^2 mod n; R = 2^(num_bits) */ > >+ rlen = (*prop)->num_bits * 2; /* #bits of R^2 = (2^num_bits)^2 */ > >+ rr[0] = 0; > >+ *(uint8_t *)&rr[0] = (1 << (rlen % 8)); > >+ for (i = 1; i < (((rlen + 31) >> 5) + 1); i++) > >+ rr[i] = 0; > >+ br_i32_decode(rrtmp, rr, ((rlen + 7) >> 3) + 1); > >+ br_i32_reduce(rr, rrtmp, n); > >+ > >+ rlen = ((*prop)->num_bits + 7) >> 3; /* #bytes of R^2 mod n */ > >+ (*prop)->rr = malloc(rlen); > >+ if (!(*prop)->rr) { > >+ ret = -ENOMEM; > >+ goto err; > >+ } > >+ br_i32_encode((void *)(*prop)->rr, rlen, rr); > >+ > >+ return 0; > >+ > >+err: > >+ free(n); > >+ free(rr); > >+ free(rrtmp); > >+ rsa_free_key_prop(*prop); > >+ return ret; > >+} > >