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Avoid integer overflow in entropy counter.

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Slightly clarify the RAND_... documentation.
This commit is contained in:
Bodo Möller 2000-01-21 19:54:22 +00:00
parent 60b5245360
commit 720b3598d6
3 changed files with 13 additions and 9 deletions
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5
crypto/rand/md_rand.c
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@ -138,7 +138,7 @@ static int state_num=0,state_index=0;
static unsigned char state[STATE_SIZE+MD_DIGEST_LENGTH]; static unsigned char state[STATE_SIZE+MD_DIGEST_LENGTH];
static unsigned char md[MD_DIGEST_LENGTH]; static unsigned char md[MD_DIGEST_LENGTH];
static long md_count[2]={0,0}; static long md_count[2]={0,0};
static int entropy=0; static unsigned entropy=0;
const char *RAND_version="RAND" OPENSSL_VERSION_PTEXT; const char *RAND_version="RAND" OPENSSL_VERSION_PTEXT;
@ -286,7 +286,8 @@ static void ssleay_rand_add(const void *buf, int num, int add)
#ifndef THREADS #ifndef THREADS
assert(md_c[1] == md_count[1]); assert(md_c[1] == md_count[1]);
#endif #endif
entropy += add; if (entropy < ENTROPY_NEEDED)
entropy += add;
} }
static void ssleay_rand_seed(const void *buf, int num) static void ssleay_rand_seed(const void *buf, int num)

2
doc/crypto/RAND_add.pod
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@ -30,7 +30,7 @@ RAND_add() may be called with sensitive data such as user entered
passwords. The seed values cannot be recovered from the PRNG output. passwords. The seed values cannot be recovered from the PRNG output.
OpenSSL makes sure that the PRNG state is unique for each thread. On OpenSSL makes sure that the PRNG state is unique for each thread. On
systems that provide C</dev/random>, the randomness device is used systems that provide C</dev/urandom>, the randomness device is used
to seed the PRNG transparently. However, on all other systems, the to seed the PRNG transparently. However, on all other systems, the
application is responsible for seeding the PRNG by calling RAND_add() application is responsible for seeding the PRNG by calling RAND_add()
or RAND_load_file(3). or RAND_load_file(3).

15
doc/crypto/RAND_bytes.pod
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@ -14,13 +14,16 @@ RAND_bytes, RAND_pseudo_bytes - Generate random data
=head1 DESCRIPTION =head1 DESCRIPTION
RAND_bytes() puts B<num> random bytes into B<buf>. An error occurs if RAND_bytes() puts B<num> cryptographically strong pseudo-random bytes
the PRNG has not been seeded with enough randomness. into B<buf>. An error occurs if the PRNG has not been seeded with
enough randomness to ensure an unpredictable byte sequence.
RAND_pseudo_bytes() puts B<num> pseudo-random bytes into B<buf>. These RAND_pseudo_bytes() puts B<num> pseudo-random bytes into B<buf>.
bytes are guaranteed to be unique, but not unpredictable. They can be Pseudo-random byte sequences generated by RAND_pseudo_bytes() will be
used for non-cryptographic purposes and for certain purposes in unique if they are of sufficient length, but are not necessarily
cryptographic protocols, but not for key generation etc. unpredictable. They can be used for non-cryptographic purposes and for
certain purposes in cryptographic protocols, but usually not for key
generation etc.
=head1 RETURN VALUES =head1 RETURN VALUES