Unable to use eddsa SSH key

[samip5]

Jenkins and plugins versions report

Environment

Jenkins: 2.440.3
OS: Linux - 5.15.103-grsec-kapsi
Java: 11.0.22 - Debian (OpenJDK 64-Bit Server VM)
---
ant:497.v94e7d9fffa_b_9
antisamy-markup-formatter:162.v0e6ec0fcfcf6
apache-httpcomponents-client-4-api:4.5.14-208.v438351942757
apache-httpcomponents-client-5-api:5.3.1-1.0
asm-api:9.7-33.v4d23ef79fcc8
authentication-tokens:1.53.v1c90fd9191a_b_
bootstrap5-api:5.3.3-1
bouncycastle-api:2.30.1.77-225.v26ea_c9455fd9
branch-api:2.1163.va_f1064e4a_a_f3
build-timeout:1.32
caffeine-api:3.1.8-133.v17b_1ff2e0599
checks-api:2.2.0
cloud-stats:336.v788e4055508b_
cloudbees-folder:6.901.vb_4c7a_da_75da_3
commons-lang3-api:3.13.0-62.v7d18e55f51e2
commons-text-api:1.11.0-109.vfe16c66636eb_
credentials:1337.v60b_d7b_c7b_c9f
credentials-binding:657.v2b_19db_7d6e6d
display-url-api:2.200.vb_9327d658781
docker-commons:439.va_3cb_0a_6a_fb_29
docker-workflow:572.v950f58993843
durable-task:555.v6802fe0f0b_82
echarts-api:5.5.0-1
email-ext:1806.v856a_01a_fa_39a_
font-awesome-api:6.5.2-1
git:5.2.1
git-client:4.7.0
github:1.38.0
github-api:1.318-461.v7a_c09c9fa_d63
github-branch-source:1787.v8b_8cd49a_f8f1
gradle:2.11
gson-api:2.10.1-15.v0d99f670e0a_7
hetzner-cloud:84.v8acf5510fd35
instance-identity:185.v303dc7c645f9
ionicons-api:70.v2959a_b_74e3cf
jackson2-api:2.17.0-379.v02de8ec9f64c
jakarta-activation-api:2.1.3-1
jakarta-mail-api:2.1.3-1
javax-activation-api:1.2.0-6
javax-mail-api:1.6.2-9
jaxb:2.3.9-1
jdk-tool:73.vddf737284550
jjwt-api:0.11.5-112.ve82dfb_224b_a_d
joda-time-api:2.12.7-29.v5a_b_e3a_82269a_
jquery3-api:3.7.1-2
json-api:20240303-41.v94e11e6de726
json-path-api:2.9.0-58.v62e3e85b_a_655
junit:1265.v65b_14fa_f12f0
kubernetes:4203.v1dd44f5b_1cf9
kubernetes-client-api:6.10.0-240.v57880ce8b_0b_2
kubernetes-credentials:0.11
mailer:472.vf7c289a_4b_420
matrix-auth:3.2.2
matrix-project:822.824.v14451b_c0fd42
metrics:4.2.21-449.v6960d7c54c69
mina-sshd-api-common:2.12.1-101.v85b_e08b_780dd
mina-sshd-api-core:2.12.1-101.v85b_e08b_780dd
oic-auth:4.250.v5a_d993226437
okhttp-api:4.11.0-172.vda_da_1feeb_c6e
permissive-script-security:0.7
pipeline-build-step:540.vb_e8849e1a_b_d8
pipeline-github-lib:42.v0739460cda_c4
pipeline-graph-analysis:216.vfd8b_ece330ca_
pipeline-groovy-lib:704.vc58b_8890a_384
pipeline-input-step:495.ve9c153f6067b_
pipeline-milestone-step:119.vdfdc43fc3b_9a_
pipeline-model-api:2.2198.v41dd8ef6dd56
pipeline-model-definition:2.2198.v41dd8ef6dd56
pipeline-model-extensions:2.2198.v41dd8ef6dd56
pipeline-rest-api:2.34
pipeline-stage-step:312.v8cd10304c27a_
pipeline-stage-tags-metadata:2.2198.v41dd8ef6dd56
pipeline-stage-view:2.34
plain-credentials:179.vc5cb_98f6db_38
plugin-util-api:4.1.0
resource-disposer:0.23
role-strategy:717.v6a_69a_fe98974
scm-api:690.vfc8b_54395023
script-security:1335.vf07d9ce377a_e
snakeyaml-api:2.2-111.vc6598e30cc65
ssh-agent:367.vf9076cd4ee21
ssh-credentials:337.v395d2403ccd4
ssh-slaves:2.948.vb_8050d697fec
sshd:3.322.v159e91f6a_550
structs:337.v1b_04ea_4df7c8
timestamper:1.26
token-macro:400.v35420b_922dcb_
trilead-api:2.142.v748523a_76693
variant:60.v7290fc0eb_b_cd
workflow-aggregator:596.v8c21c963d92d
workflow-api:1291.v51fd2a_625da_7
workflow-basic-steps:1058.vcb_fc1e3a_21a_9
workflow-cps:3894.vd0f0248b_a_fc4
workflow-durable-task-step:1336.v768003e07199
workflow-job:1400.v7fd111b_ec82f
workflow-multibranch:773.vc4fe1378f1d5
workflow-scm-step:427.v4ca_6512e7df1
workflow-step-api:657.v03b_e8115821b_
workflow-support:896.v175a_a_9c5b_78f
ws-cleanup:0.45

What Operating System are you using (both controller, and any agents involved in the problem)?

Controller is running Debian 12.

Reproduction steps

1. Create a SSH key that's not RSA
2. Try to build

Expected Results

I expected it to have no issues.

Actual Results

Nothing was provisioned.

Anything else?

java.lang.ClassCastException: class net.i2p.crypto.eddsa.EdDSAPublicKey cannot be cast to class java.security.interfaces.RSAPublicKey (net.i2p.crypto.eddsa.EdDSAPublicKey is in unnamed module of loader jenkins.util.URLClassLoader2 @328d6483; java.security.interfaces.RSAPublicKey is in module java.base of loader 'bootstrap')
	at cloud.dnation.jenkins.plugins.hetzner.Helper.getSSHPublicKeyFromPrivate(Helper.java:74)
	at cloud.dnation.jenkins.plugins.hetzner.HetznerCloudResourceManager.getOrCreateSshKey(HetznerCloudResourceManager.java:205)
	at cloud.dnation.jenkins.plugins.hetzner.HetznerCloudResourceManager.createServer(HetznerCloudResourceManager.java:243)
	at cloud.dnation.jenkins.plugins.hetzner.NodeCallable.call(NodeCallable.java:42)
	at cloud.dnation.jenkins.plugins.hetzner.NodeCallable.call(NodeCallable.java:30)
	at jenkins.util.ContextResettingExecutorService$2.call(ContextResettingExecutorService.java:46)
	at jenkins.security.ImpersonatingExecutorService$2.call(ImpersonatingExecutorService.java:80)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)

Are you interested in contributing a fix?

No response

[rkosegi]

Thanks for bug report.
Indeed, ED25519 keys are not supported currently.
Should be fixed soon