'\" te
.\" Copyright (c) 2007, 2012, Oracle and/or its affiliates. All rights reserved.
.TH sha2 3EXT "20 Feb 2012" "SunOS 5.11" "Extended Library Functions"
.SH NAME
sha2, SHA2Init, SHA2Update, SHA2Final, SHA224Init, SHA224Update, SHA224Final, SHA256Init, SHA256Update, SHA256Final, SHA384Init, SHA384Update, SHA384Final, SHA512Init, SHA512Update, SHA512Final \- SHA2 digest functions
.SH SYNOPSIS
.LP
.nf
\fBcc\fR [ \fIflag\fR ... ] \fIfile\fR ... \fB-lmd\fR [ \fIlibrary\fR ... ]
#include <sha2.h>

\fBvoid\fR \fBSHA2Init\fR(\fBuint64_t\fR \fImech\fR, \fBSHA2_CTX *\fR\fIcontext\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA2Update\fR(\fBSHA2_CTX *\fR\fIcontext\fR, \fBunsigned char *\fR\fIinput\fR,
     \fBunsigned int\fR \fIinlen\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA2Final\fR(\fBunsigned char *\fR\fIoutput\fR, \fBSHA2_CTX *\fR\fIcontext\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA224Init\fR(\fBSHA224_CTX *\fR\fIcontext\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA224Update\fR(\fBSHA224_CTX *\fR\fIcontext\fR, \fBunsigned char *\fR\fIinput\fR,
     \fBunsigned int\fR \fIinlen\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA224Final\fR(\fBunsigned char *\fR\fIoutput\fR, \fBSHA224_CTX *\fR\fIcontext\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA256Init\fR(\fBSHA256_CTX *\fR\fIcontext\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA256Update\fR(\fBSHA256_CTX *\fR\fIcontext\fR, \fBunsigned char *\fR\fIinput\fR,
     \fBunsigned int\fR \fIinlen\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA256Final\fR(\fBunsigned char *\fR\fIoutput\fR, \fBSHA256_CTX *\fR\fIcontext\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA384Init\fR(\fBSHA384_CTX *\fR\fIcontext\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA384Update\fR(\fBSHA384_CTX *\fR\fIcontext\fR, \fBunsigned char *\fR\fIinput\fR,
     \fBunsigned int\fR \fIinlen\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA384Final\fR(\fBunsigned char *\fR\fIoutput\fR, \fBSHA384_CTX *\fR\fIcontext\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA512Init\fR(\fBSHA512_CTX *\fR\fIcontext\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA512Update\fR(\fBSHA512_CTX *\fR\fIcontext\fR, \fBunsigned char *\fR\fIinput\fR,
     \fBunsigned int\fR \fIinlen\fR);
.fi

.LP
.nf
\fBvoid\fR \fBSHA512Final\fR(\fBunsigned char *\fR\fIoutput\fR, \fBSHA512_CTX *\fR\fIcontext\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBSHA2Init()\fR, \fBSHA2Update()\fR, \fBSHA2Final()\fR functions implement the \fBSHA224\fR, \fBSHA256\fR, \fBSHA384\fR and \fBSHA512\fR message-digest algorithms. The algorithms take as input a message of arbitrary length and produces a 200-bit "fingerprint" or "message digest" as output. The \fBSHA2\fR message-digest algorithms are intended for digital signature applications in which large files are "compressed" in a secure manner before being encrypted with a private (secret) key under a public-key cryptosystem such as RSA.
.sp
.ne 2
.mk
.na
\fB\fBSHA2Init()\fR, \fBSHA2Update()\fR, \fBSHA2Final()\fR\fR
.ad
.sp .6
.RS 4n
The \fBSHA2Init()\fR, \fBSHA2Update()\fR, and \fBSHA2Final()\fR functions allow an \fBSHA2\fR digest to be computed over multiple message blocks. Between blocks, the state of the \fBSHA2\fR computation is held in an \fBSHA2\fR context structure allocated by the caller. A complete digest computation consists of calls to \fBSHA2\fR functions in the following order: one call to \fBSHA2Init()\fR, one or more calls to \fBSHA2Update()\fR, and one call to \fBSHA2Final()\fR.
.sp
The \fBSHA2Init()\fR function initializes the SHA2 context structure pointed to by \fIcontext\fR. The \fImech\fR argument is one of \fBSHA224\fR, \fBSHA256\fR, \fBSHA512\fR, and \fBSHA384\fR.
.sp
The \fBSHA2Update()\fR function computes a partial \fBSHA2\fR digest on the \fIinlen\fR-byte message block pointed to by \fIinput\fR, and updates the \fBSHA2\fR context structure pointed to by \fIcontext\fR accordingly.
.sp
The \fBSHA2Final()\fR function generates the final \fBSHA2Final\fR digest, using the \fBSHA2\fR context structure pointed to by \fIcontext\fR. The \fBSHA2\fR digest is written to output. After a call to \fBSHA2Final()\fR, the state of the context structure is undefined. It must be reinitialized with \fBSHA2Init()\fR before it can be used again.
.RE

.sp
.ne 2
.mk
.na
\fB\fBSHA224Init()\fR, \fBSHA224Update()\fR, \fBSHA224Final()\fR, \fBSHA256Init()\fR, \fBSHA256Update()\fR, \fBSHA256Final()\fR, \fBSHA384Init()\fR, \fBSHA384Update()\fR, \fBSHA384Final()\fR, \fBSHA512Init()\fR, \fBSHA512Update()\fR, \fBSHA512Final()\fR\fR
.ad
.sp .6
.RS 4n
Alternative APIs exist as named above. The \fBUpdate()\fR and \fBFinal()\fR sets of functions operate exactly as the previously described \fBSHA2Update()\fR and \fBSHA2Final()\fR functions. The \fBSHA224Init()\fR, \fBSHA256Init()\fR, \fBSHA384Init()\fR, and \fBSHA512Init()\fR functions do not take the \fImech\fR argument as it is implicit in the function names.
.RE

.SH RETURN VALUES
.sp
.LP
These functions do not return a value.
.SH EXAMPLES
.LP
\fBExample 1 \fRAuthenticate a message found in multiple buffers
.sp
.LP
The following is a sample function that authenticates a message found in multiple buffers. The calling function provides an authentication buffer to contain the result of the \fBSHA2\fR digest.

.sp
.in +2
.nf
#include <sys/types.h>
#include <sys/uio.h>
#include <sha2.h>

int
AuthenticateMsg(unsigned char *auth_buffer, struct iovec 
                *messageIov, unsigned int num_buffers)
{
    SHA2_CTX sha2_context;
    unsigned int i;

    SHA2Init(SHA384, &sha2_context);

    for(i=0; i<num_buffers; i++)
    {
         SHA2Update(&sha2_context, messageIov->iov_base,
                   messageIov->iov_len);
         messageIov += sizeof(struct iovec);
    }

    SHA2Final(auth_buffer, &sha2_context);

    return 0;
}
.fi
.in -2

.LP
\fBExample 2 \fRAuthenticate a message found in multiple buffers
.sp
.LP
The following is a sample function that authenticates a message found in multiple buffers. The calling function provides an authentication buffer that will contain the result of the \fBSHA384\fR digest, using alternative interfaces.

.sp
.in +2
.nf
int
AuthenticateMsg(unsigned char *auth_buffer, struct iovec 
                *messageIov, unsigned int num_buffers)
{
    SHA384_CTX ctx;
    unsigned int i;

    SHA384Init(&ctx);

    for(i=0, i<num_buffers; i++
    {
         SHA384Update(&ctx, messageIov->iov_base,
                   messageIov->iov_len);
         messageIov += sizeof(struct iovec);
    }

    SHA384Final(auth_buffer, &ctx);

    return 0;
}
.fi
.in -2

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
tab() box;
cw(2.75i) |cw(2.75i) 
lw(2.75i) |lw(2.75i) 
.
ATTRIBUTE TYPEATTRIBUTE VALUE
_
Interface StabilityCommitted
_
MT-LevelMT-Safe
.TE

.SH SEE ALSO
.sp
.LP
\fBlibmd\fR(3LIB)
.sp
.LP
FIPS 180-2