From 26a029d407be480d791972afb5975cf62c9360a6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Fri, 19 Apr 2024 02:47:55 +0200 Subject: Adding upstream version 124.0.1. Signed-off-by: Daniel Baumann --- security/nss/lib/freebl/ecl/README | 163 +++++++++++++++++++++++++++++++++++++ 1 file changed, 163 insertions(+) create mode 100644 security/nss/lib/freebl/ecl/README (limited to 'security/nss/lib/freebl/ecl/README') diff --git a/security/nss/lib/freebl/ecl/README b/security/nss/lib/freebl/ecl/README new file mode 100644 index 0000000000..2996822c88 --- /dev/null +++ b/security/nss/lib/freebl/ecl/README @@ -0,0 +1,163 @@ +This Source Code Form is subject to the terms of the Mozilla Public +License, v. 2.0. If a copy of the MPL was not distributed with this +file, You can obtain one at http://mozilla.org/MPL/2.0/. + +The ECL exposes routines for constructing and converting curve +parameters for internal use. + + +HEADER FILES +============ + +ecl-exp.h - Exports data structures and curve names. For use by code +that does not have access to mp_ints. + +ecl-curve.h - Provides hex encodings (in the form of ECCurveParams +structs) of standardizes elliptic curve domain parameters and mappings +from ECCurveName to ECCurveParams. For use by code that does not have +access to mp_ints. + +ecl.h - Interface to constructors for curve parameters and group object, +and point multiplication operations. Used by higher level algorithms +(like ECDH and ECDSA) to actually perform elliptic curve cryptography. + +ecl-priv.h - Data structures and functions for internal use within the +library. + +ecp.h - Internal header file that contains all functions for point +arithmetic over prime fields. + +DATA STRUCTURES AND TYPES +========================= + +ECCurveName (from ecl-exp.h) - Opaque name for standardized elliptic +curve domain parameters. + +ECCurveParams (from ecl-exp.h) - Provides hexadecimal encoding +of elliptic curve domain parameters. Can be generated by a user +and passed to ECGroup_fromHex or can be generated from a name by +EC_GetNamedCurveParams. ecl-curve.h contains ECCurveParams structs for +the standardized curves defined by ECCurveName. + +ECGroup (from ecl.h and ecl-priv.h) - Opaque data structure that +represents a group of elliptic curve points for a particular set of +elliptic curve domain parameters. Contains all domain parameters (curve +a and b, field, base point) as well as pointers to the functions that +should be used for point arithmetic and the underlying field GFMethod. +Generated by either ECGroup_fromHex or ECGroup_fromName. + +GFMethod (from ecl-priv.h) - Represents a field underlying a set of +elliptic curve domain parameters. Contains the irreducible that defines +the field (either the prime or the binary polynomial) as well as +pointers to the functions that should be used for field arithmetic. + +ARITHMETIC FUNCTIONS +==================== + +Higher-level algorithms (like ECDH and ECDSA) should call ECPoint_mul +or ECPoints_mul (from ecl.h) to do point arithmetic. These functions +will choose which underlying algorithms to use, based on the ECGroup +structure. + +Point Multiplication +-------------------- + +ecl_mult.c provides the ECPoints_mul and ECPoint_mul wrappers. +It also provides two implementations for the pts_mul operation - +ec_pts_mul_basic (which computes kP, lQ, and then adds kP + lQ) and +ec_pts_mul_simul_w2 (which does a simultaneous point multiplication +using a table with window size 2*2). + +ec_naf.c provides an implementation of an algorithm to calculate a +non-adjacent form of a scalar, minimizing the number of point +additions that need to be done in a point multiplication. + +Point Arithmetic over Prime Fields +---------------------------------- + +ecp_aff.c provides point arithmetic using affine coordinates. + +ecp_jac.c provides point arithmetic using Jacobian projective +coordinates and mixed Jacobian-affine coordinates. (Jacobian projective +coordinates represent a point (x, y) as (X, Y, Z), where x=X/Z^2, +y=Y/Z^3). + +ecp_jm.c provides point arithmetic using Modified Jacobian +coordinates and mixed Modified_Jacobian-affine coordinates. +(Modified Jacobian coordinates represent a point (x, y) +as (X, Y, Z, a*Z^4), where x=X/Z^2, y=Y/Z^3, and a is +the linear coefficient in the curve defining equation). + +ecp_192.c and ecp_224.c provide optimized field arithmetic. + +Field Arithmetic +---------------- + +ecl_gf.c provides constructors for field objects (GFMethod) with the +functions GFMethod_cons*. It also provides wrappers around the basic +field operations. + +Prime Field Arithmetic +---------------------- + +The mpi library provides the basic prime field arithmetic. + +ecp_mont.c provides wrappers around the Montgomery multiplication +functions from the mpi library and adds encoding and decoding functions. +It also provides the function to construct a GFMethod object using +Montgomery multiplication. + +ecp_192.c and ecp_224.c provide optimized modular reduction for the +fields defined by nistp192 and nistp224 primes. + +ecl_gf.c provides wrappers around the basic field operations. + +Field Encoding +-------------- + +By default, field elements are encoded in their basic form. It is +possible to use an alternative encoding, however. For example, it is +possible to Montgomery representation of prime field elements and +take advantage of the fast modular multiplication that Montgomery +representation provides. The process of converting from basic form to +Montgomery representation is called field encoding, and the opposite +process would be field decoding. All internal point operations assume +that the operands are field encoded as appropriate. By rewiring the +underlying field arithmetic to perform operations on these encoded +values, the same overlying point arithmetic operations can be used +regardless of field representation. + +ALGORITHM WIRING +================ + +The EC library allows point and field arithmetic algorithms to be +substituted ("wired-in") on a fine-grained basis. This allows for +generic algorithms and algorithms that are optimized for a particular +curve, field, or architecture, to coexist and to be automatically +selected at runtime. + +Wiring Mechanism +---------------- + +The ECGroup and GFMethod structure contain pointers to the point and +field arithmetic functions, respectively, that are to be used in +operations. + +The selection of algorithms to use is handled in the function +ecgroup_fromNameAndHex in ecl.c. + +Default Wiring +-------------- + +Curves over prime fields by default use montgomery field arithmetic, +point multiplication using 5-bit window non-adjacent-form with +Modified Jacobian coordinates, and 2*2-bit simultaneous point +multiplication using Jacobian coordinates. +(Wiring in function ECGroup_consGFp_mont in ecl.c.) + +Curves over prime fields that have optimized modular reduction (i.e., +secp160r1, nistp192, and nistp224) do not use Montgomery field +arithmetic. Instead, they use basic field arithmetic with their +optimized reduction (as in ecp_192.c and ecp_224.c). They +use the same point multiplication and simultaneous point multiplication +algorithms as other curves over prime fields. -- cgit v1.2.3