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CH08: Move serialization of ECDSA signatures

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David A. Harding 2023-04-08 08:50:09 -10:00
parent 237fd1ea50
commit afed975b8c
1 changed files with 30 additions and 30 deletions
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chapters/signatures.adoc
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@ -95,35 +95,6 @@ called the
_Distinguished Encoding Rules_, or _DER_. For schnorr signatures, a
simpler serialization format is used.
[[serialization_of_signatures_der]]
===== Serialization of ECDSA signatures (DER)
Let's look at
the following DER-encoded signature:
----
3045022100884d142d86652a3f47ba4746ec719bbfbd040a570b1deccbb6498c75c4ae24cb02204b9f039ff08df09cbe9f6addac960298cad530a863ea8f53982c09db8f6e381301
----
That signature is a serialized byte-stream of the +R+ and +S+ values
produced by to prove control of the private key authorized
to spend an output. The serialization format consists of nine elements
as follows:
* +0x30+—indicating the start of a DER sequence
* +0x45+—the length of the sequence (69 bytes)
* +0x02+—an integer value follows
* +0x21+—the length of the integer (33 bytes)
* +R+—++00884d142d86652a3f47ba4746ec719bbfbd040a570b1deccbb6498c75c4ae24cb++
* +0x02+—another integer follows
* +0x20+—the length of the integer (32 bytes)
* +S+—++4b9f039ff08df09cbe9f6addac960298cad530a863ea8f53982c09db8f6e3813++
* A suffix (+0x01+) indicating the type of hash used (+SIGHASH_ALL+)
See if you can decode Alice's serialized (DER-encoded) signature using
this list. The important numbers are +R+ and +S+; the rest of the data
is part of the DER encoding scheme.
==== Verifying the Signature
((("digital signatures", "verifying")))To verify the signature, one must
@ -337,7 +308,36 @@ online take you through it step by step: search for "ECDSA explained" or
try this one: http://bit.ly/2r0HhGB[].
====
==== The Importance of Randomness in Signatures
[[serialization_of_signatures_der]]
==== Serialization of ECDSA signatures (DER)
Let's look at
the following DER-encoded signature:
----
3045022100884d142d86652a3f47ba4746ec719bbfbd040a570b1deccbb6498c75c4ae24cb02204b9f039ff08df09cbe9f6addac960298cad530a863ea8f53982c09db8f6e381301
----
That signature is a serialized byte-stream of the +R+ and +S+ values
produced by to prove control of the private key authorized
to spend an output. The serialization format consists of nine elements
as follows:
* +0x30+—indicating the start of a DER sequence
* +0x45+—the length of the sequence (69 bytes)
* +0x02+—an integer value follows
* +0x21+—the length of the integer (33 bytes)
* +R+—++00884d142d86652a3f47ba4746ec719bbfbd040a570b1deccbb6498c75c4ae24cb++
* +0x02+—another integer follows
* +0x20+—the length of the integer (32 bytes)
* +S+—++4b9f039ff08df09cbe9f6addac960298cad530a863ea8f53982c09db8f6e3813++
* A suffix (+0x01+) indicating the type of hash used (+SIGHASH_ALL+)
See if you can decode Alice's serialized (DER-encoded) signature using
this list. The important numbers are +R+ and +S+; the rest of the data
is part of the DER encoding scheme.
=== The Importance of Randomness in Signatures
((("digital signatures", "randomness in")))As we saw in <<ecdsa_math>>,
the signature generation algorithm uses a random key _k_, as the basis