Shrink the maintained fork and bump BouncyCastle for downstream

jgit-gpg-bc/build.gradle.kts

@@ -2,14 +2,14 @@ plugins {
     id("org.openrewrite.build.language-library")
 }
 
-val bcVersion = "1.70"
+val bcVersion = "1.85"
+val bcProvVersion = "1.85.2"
 dependencies {
     implementation(project(":jgit"))
     compileOnly("org.slf4j:slf4j-api:1.7.36")
-    implementation("org.bouncycastle:bcpg-jdk15on:$bcVersion")
-    implementation("org.bouncycastle:bcprov-jdk15on:$bcVersion")
-    implementation("org.bouncycastle:bcutil-jdk15on:$bcVersion")
-    implementation("org.bouncycastle:bcpkix-jdk15on:$bcVersion")
+    implementation("org.bouncycastle:bcpg-jdk18on:$bcVersion")
+    implementation("org.bouncycastle:bcprov-jdk18on:$bcProvVersion")
+    implementation("org.bouncycastle:bcutil-jdk18on:$bcVersion")
 }
 
 java {

jgit-gpg-bc/src/main/java/org/openrewrite/jgit/gpg/bc/internal/BCText.java

@@ -29,6 +29,7 @@ public static BCText get() {
 	// @formatter:off
 	/***/ public String corrupt25519Key;
 	/***/ public String credentialPassphrase;
+	/***/ public String cryptAeadUnsupported;
 	/***/ public String cryptCipherError;
 	/***/ public String cryptWrongDecryptedLength;
 	/***/ public String gpgFailedToParseSecretKey;

jgit-gpg-bc/src/main/java/org/openrewrite/jgit/gpg/bc/internal/keys/OCBPBEProtectionRemoverFactory.java

@@ -67,6 +67,15 @@ public PBESecretKeyDecryptor createDecryptor(String protection)
 			throws PGPException {
 		return new PBESecretKeyDecryptor(passphrase, calculatorProvider) {
 
+			@Override
+			public byte[] recoverKeyData(int encAlgorithm, int aeadAlgorithm,
+					byte[] key, byte[] iv, int packetTag, int keyVersion,
+					byte[] keyData, byte[] pubkeyData) throws PGPException {
+				// The AAD is fixed at factory level, so this decryptor cannot
+				// serve the v6 key format, which derives it per key.
+				throw new PGPException(BCText.get().cryptAeadUnsupported);
+			}
+
 			@Override
 			public byte[] recoverKeyData(int encAlgorithm, byte[] key,
 					byte[] iv, byte[] encrypted, int encryptedOffset,

jgit-gpg-bc/src/main/resources/org/openrewrite/jgit/gpg/bc/internal/BCText.properties

@@ -40,6 +40,7 @@
 
 corrupt25519Key=Ed25519/Curve25519 public key has wrong length: {0}
 credentialPassphrase=Passphrase
+cryptAeadUnsupported=Cannot decrypt AEAD-protected secret keys in the OpenPGP v6 key format
 cryptCipherError=Cannot create cipher to decrypt: {0}
 cryptWrongDecryptedLength=Decrypted key has wrong length; expected {0} bytes, got only {1} bytes
 gpgFailedToParseSecretKey=Failed to parse secret key file {0}. Is the entered passphrase correct?