Contents

# Multi-buffer Cryptography Functions

## Introduction

Crypto_mb
library implements well known cryptography algorithms. The feature of
Crypto_mb
is application of the usual cryptography algorithm to different independent data in parallel.
For example, instead of usual (scalar) RSA decryption
x = y
d
mod n
,
Crpto_mb
consider vector operation
x[i] = y[i]
d[i]
mod n[i]
,
0<=i<8
, where all eight operations run simultaneously. The single limitation is the requirement that all the data must be compatible in terms of size. Thus, RSAs moduli
n[i]
must be the same size, as well as ciphertext
y[i]
and recovered text
x[i]
.
Together with new integer AVX512 instructions, this approach provides performance benefit in comparison with scalar approach. This feature of the
Crypto_mb
affects server and cloud applications positively.
Currently
Crypto_mb
supports:
• RSA encryption and decryption of 1, 2 3 and 4Kb
• ECDSA and ECDH/DHE over NIST recommended Elliptic Curves P256, P384 and P521
• ECDH/DHE over Curve25519

## APIs, Parameters and Data Representation

Public APIs use parameters that are directly present in the math description of algorithm, avoiding aggregated data structures. Usually, parameters of public APIs are "arrays of pointers to data vectors".
Input and output data is represented as a big endian byte string (i.e. leftmost byte is the most significant and rightmost byte is less significant) of suitable length. The exception is X25519 functional, where a private key is represented as a little endian byte string.
Usually, key stuff (public and private key components) are multi-precision positive integers represented in the memory as a vector of digits in base
B (B = 2
64
)
. Thus,
L
-digit non-negative integer value
x
in base
B
is represented as follows:
x = x*B
0
+ x*B
1
+ … + x[L-1]*B
(L-1)
.
In case of OpenSSL-like APIs, the parameters, where it is applicable, are represented by BIGNUM datatype as is customary in OpenSSL.

## Return value

APIs return 32-bit group status, allowing to parse each of eight components connected with particular processed dataset. The function
mbx_status MBX_GET_STS(mbx_status status, int numb)
extracts from the group status specified by the
status
parameter and returns the status value corresponding to the processed dataset specified by the
numb
parameter. Return value is one of the following:
• MBX_STATUS_OK
- operation competed successfully
• MBX_STATUS_MISMATCH_PARAM_ERR
- operation detected any incompatibility in parameters
• MBX_STATUS_NULL_PARAM_ERR
- operation detected NULL pointer
• MBX_STATUS_LOW_ORDER_ERR
- computed shared secret is zero
• MBX_STATUS_SIGNATURE_ERR
- r- or s- component of generated signature is zero

#### Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.