ENHANCED: Eliminate the OpenSSL dependency of library(crypto).

This is achieved by using the newly available crrl crate by @pornin
to implement crypto_curve_scalar_mult/4 for secp256k1. Many thanks!

Cargo.lock

@@ -78,10 +78,19 @@ checksum = "94cb07b0da6a73955f8fb85d24c466778e70cda767a568229b104f0264089330"
 dependencies = [
  "byte-tools",
  "crypto-mac",
- "digest",
+ "digest 0.8.1",
  "opaque-debug",
 ]
 
+[[package]]
+name = "blake2"
+version = "0.10.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9cf849ee05b2ee5fba5e36f97ff8ec2533916700fc0758d40d92136a42f3388"
+dependencies = [
+ "digest 0.10.3",
+]
+
 [[package]]
 name = "block-buffer"
 version = "0.7.3"
@@ -91,7 +100,16 @@ dependencies = [
  "block-padding",
  "byte-tools",
  "byteorder",
- "generic-array",
+ "generic-array 0.12.4",
+]
+
+[[package]]
+name = "block-buffer"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0bf7fe51849ea569fd452f37822f606a5cabb684dc918707a0193fd4664ff324"
+dependencies = [
+ "generic-array 0.14.6",
 ]
 
 [[package]]
@@ -209,6 +227,15 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "cpufeatures"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc948ebb96241bb40ab73effeb80d9f93afaad49359d159a5e61be51619fe813"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "crossterm"
 version = "0.20.0"
@@ -234,14 +261,35 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "crrl"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2db40892a506901e4e8281f00e42687df82d1d3448cb0289ae9183a60cb42ec1"
+dependencies = [
+ "blake2 0.10.4",
+ "rand_core 0.6.3",
+ "sha2",
+]
+
+[[package]]
+name = "crypto-common"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1bfb12502f3fc46cca1bb51ac28df9d618d813cdc3d2f25b9fe775a34af26bb3"
+dependencies = [
+ "generic-array 0.14.6",
+ "typenum",
+]
+
 [[package]]
 name = "crypto-mac"
 version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4434400df11d95d556bac068ddfedd482915eb18fe8bea89bc80b6e4b1c179e5"
 dependencies = [
- "generic-array",
- "subtle",
+ "generic-array 0.12.4",
+ "subtle 1.0.0",
 ]
 
 [[package]]
@@ -266,7 +314,18 @@ version = "0.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f3d0c8c8752312f9713efd397ff63acb9f85585afbf179282e720e7704954dd5"
 dependencies = [
- "generic-array",
+ "generic-array 0.12.4",
+]
+
+[[package]]
+name = "digest"
+version = "0.10.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2fb860ca6fafa5552fb6d0e816a69c8e49f0908bf524e30a90d97c85892d506"
+dependencies = [
+ "block-buffer 0.10.2",
+ "crypto-common",
+ "subtle 2.4.1",
 ]
 
 [[package]]
@@ -518,6 +577,16 @@ dependencies = [
  "typenum",
 ]
 
+[[package]]
+name = "generic-array"
+version = "0.14.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bff49e947297f3312447abdca79f45f4738097cc82b06e72054d2223f601f1b9"
+dependencies = [
+ "typenum",
+ "version_check",
+]
+
 [[package]]
 name = "getrandom"
 version = "0.2.6"
@@ -1087,15 +1156,6 @@ version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ff011a302c396a5197692431fc1948019154afc178baf7d8e37367442a4601cf"
 
-[[package]]
-name = "openssl-src"
-version = "111.18.0+1.1.1n"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7897a926e1e8d00219127dc020130eca4292e5ca666dd592480d72c3eca2ff6c"
-dependencies = [
- "cc",
-]
-
 [[package]]
 name = "openssl-sys"
 version = "0.9.72"
@@ -1105,7 +1165,6 @@ dependencies = [
  "autocfg 1.1.0",
  "cc",
  "libc",
- "openssl-src",
  "pkg-config",
  "vcpkg",
 ]
@@ -1565,8 +1624,8 @@ version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ad5112e0dbbb87577bfbc56c42450235e3012ce336e29c5befd7807bd626da4a"
 dependencies = [
- "block-buffer",
- "digest",
+ "block-buffer 0.7.3",
+ "digest 0.8.1",
  "opaque-debug",
 ]
 
@@ -1671,10 +1730,11 @@ version = "0.9.0"
 dependencies = [
  "assert_cmd",
  "base64",
- "blake2",
+ "blake2 0.8.1",
  "chrono",
  "cpu-time",
  "crossterm",
+ "crrl",
  "ctrlc",
  "dirs-next",
  "divrem",
@@ -1691,7 +1751,6 @@ dependencies = [
  "modular-bitfield",
  "native-tls",
  "num-rug-adapter",
- "openssl",
  "ordered-float",
  "phf 0.9.0",
  "predicates-core",
@@ -1802,15 +1861,26 @@ dependencies = [
  "syn 1.0.90",
 ]
 
+[[package]]
+name = "sha2"
+version = "0.10.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf9db03534dff993187064c4e0c05a5708d2a9728ace9a8959b77bedf415dac5"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest 0.10.3",
+]
+
 [[package]]
 name = "sha3"
 version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dd26bc0e7a2e3a7c959bc494caf58b72ee0c71d67704e9520f736ca7e4853ecf"
 dependencies = [
- "block-buffer",
+ "block-buffer 0.7.3",
  "byte-tools",
- "digest",
+ "digest 0.8.1",
  "keccak",
  "opaque-debug",
 ]
@@ -1974,6 +2044,12 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2d67a5a62ba6e01cb2192ff309324cb4875d0c451d55fe2319433abe7a05a8ee"
 
+[[package]]
+name = "subtle"
+version = "2.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6bdef32e8150c2a081110b42772ffe7d7c9032b606bc226c8260fd97e0976601"
+
 [[package]]
 name = "syn"
 version = "0.15.44"
@@ -2219,6 +2295,12 @@ version = "0.2.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "accd4ea62f7bb7a82fe23066fb0957d48ef677f6eeb8215f372f52e48bb32426"
 
+[[package]]
+name = "version_check"
+version = "0.9.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
+
 [[package]]
 name = "wait-timeout"
 version = "0.2.0"