diff --git a/app/lib/activitypub/object_integrity_proof.rb b/app/lib/activitypub/object_integrity_proof.rb
index e6d84c2b937..a5f2bf9cafa 100644
--- a/app/lib/activitypub/object_integrity_proof.rb
+++ b/app/lib/activitypub/object_integrity_proof.rb
@@ -4,6 +4,8 @@
 class ActivityPub::ObjectIntegrityProof
   include JsonLdHelper
 
+  SUPPORTED_CRYPTOSUITES = %w(eddsa-jcs-2022 mldsa44-jcs-2024).freeze
+
   def initialize(json)
     @json = json
   end
@@ -19,13 +21,22 @@ class ActivityPub::ObjectIntegrityProof
     cryptosuite = proof['cryptosuite']
     key_uri = proof['verificationMethod']
 
-    return unless cryptosuite == 'eddsa-jcs-2022' && proof['proofValue'].present?
+    return unless SUPPORTED_CRYPTOSUITES.include?(cryptosuite) && proof['proofValue'].present?
 
     keypair = Keypair.from_keyid(key_uri)
     keypair = ActivityPub::FetchRemoteKeyService.new.call(key_uri) if keypair&.public_key.blank?
-    return if keypair.nil? || !keypair.usable? || keypair.type != 'ed25519'
+    return if keypair.nil? || !keypair.usable?
 
-    keypair.actor if ActivityPub::ObjectIntegrityProof.verify_eddsa_jcs_2022(@json, keypair.keypair)
+    case cryptosuite
+    when 'eddsa-jcs-2022'
+      return if keypair.type != 'ed25519'
+
+      keypair.actor if ActivityPub::ObjectIntegrityProof.verify_eddsa_jcs_2022(@json, keypair.keypair)
+    when 'mldsa44-jcs-2024'
+      return if keypair.type != 'ml-dsa-44'
+
+      keypair.actor if ActivityPub::ObjectIntegrityProof.verify_mldsa44_jcs_2024(@json, keypair.keypair)
+    end
   rescue Multibase::Error, OpenSSL::PKey::PKeyError
     false
   end
@@ -51,4 +62,21 @@ class ActivityPub::ObjectIntegrityProof
 
     keypair.verify(nil, proof_bytes, to_be_verified)
   end
+
+  # https://www.w3.org/TR/2026/WD-vc-di-quantum-resistant-1.0-20260616/#verify-proof-ml-dsa
+  def self.verify_mldsa44_jcs_2024(document, keypair) # rubocop:disable Naming/VariableNumber
+    unsecured_document = document.without('proof')
+    proof_options = document['proof'].without('proofValue')
+    proof_bytes = Multibase.decode(document['proof']['proofValue'])
+
+    # This is inconsistent with eddsa-jcs-2022 but described in https://www.w3.org/TR/2026/WD-vc-di-quantum-resistant-1.0-20260616/#ProofConfigurationAlg
+    proof_options['@context'] = unsecured_document['@context']
+
+    transformed_data = unsecured_document.to_json_c14n
+    proof_config = proof_options.to_json_c14n
+
+    to_be_verified = Digest::SHA256.digest(proof_config) + Digest::SHA256.digest(transformed_data)
+
+    keypair.verify(nil, proof_bytes, to_be_verified)
+  end
 end
diff --git a/spec/lib/activitypub/object_integrity_proof_spec.rb b/spec/lib/activitypub/object_integrity_proof_spec.rb
index 10e4e105215..46f8ff05019 100644
--- a/spec/lib/activitypub/object_integrity_proof_spec.rb
+++ b/spec/lib/activitypub/object_integrity_proof_spec.rb
@@ -217,4 +217,81 @@ RSpec.describe ActivityPub::ObjectIntegrityProof do
       end
     end
   end
+
+  describe 'verify_mldsa44_jcs_2024', skip: 'waiting for ubuntu-26.04 runners' do
+    # https://www.w3.org/TR/2026/WD-vc-di-quantum-resistant-1.0-20260616/#example-signed-credential-mldsa44-jcs-2024
+
+    let(:keypair) do
+      _, pem = Multibase.decode_key_to_pem(
+        'ukCRKDtY8Do_dXzYGyuX7BY-1dDYM4FuSiw0gFdO-eJXFH0eqlt4_CP4sEISGAzNlKDzLpUJWoInRywXOpd7FCp_QAJAlL7iRo4cepKhzhlq8xt6qd5jkhYF9tNH8z3RGDl9aunNy_06fWLYNScWd5RmGg46Po8T-kIjMMkJftaqqZcGDxktpu9Et2bnaZMx4K98YyG1urUpM9lgvldgg2qv-6XCrm2uXlJ9U-HN4xtQKn4Ug-5xPwbhPGR2pbcBScTFotkhBqLc2eQLL6zPutWF83sSZbOhD_11BjMkeiLyJbMeHCIhz5GDIbPksEFIaSho3MdFo5fpQ8QZoqCit3Jn4ddfuShfIoLU1Hw5EZ0xBiqOU7e-TINd7-7HsgHLmYMGnpqljm1ot3c3cfalYsg87WQuSscO7XNH3Ewa-cgU6Bnj1SGn0plTy6Yq-GxU8XUBPwsK_IoIJbXWC0UD97c9UYpNiZi0-ECnbB-Y5_SM8auMfoIeap_buAOdXlJZmcp8xNCXI59AN9-96Sdhks5L-JmsELzyjAgjqNx8Zt3KPFc2jSwNjDVC1fEa8FdDdDT3WNkF6KTt65lb5_aIkFh20nOvT7kIJcKTgmhRGNJZgGSPYVbMypaQoaac8dtEoQjvYgnO-rM_RcsiWMHNc29br3o5wdiLXdr63MoX1lEWu_THBfeP1JuxrSbUmHOByepWbubbSM4iVQITCxBHZT0Mj2bWwIxd3nZUajzebyEnsfitV01kpzlO7bzY2uxSzyplTkRfppc_7YH0y0PHaggw0cIXNSh73wVqNZmzmJx5W0_akrvy5oSz9ZB1Io2p_fTxzibefwO700bUqbElV_yuCjD7EJ_Hfqbog80y_g9TK6koX7wYwqFNQxBVavKC-HbcT7yPdvzs9hlC2MNWCT3W7gVgeYr4AFgbV9EgMcH0GtJDKYw8vkpB_vTsaSTGZAj3TNKalAwiGO50VAmF5tknF96kOrWmNL0MdkXhnm1vXgDpP68bMt4r2Qr-hNdJ4s3_nqmSDYTnZRA4qjXjrgKQfO19txt0tX7LifE1GZ1bQyS7NqHWXyMEhw6_F8pc_tS16VhvJO_FM7CX51mLLkLCGl7DsmbnEIsVUW9qlCxb6bj53UyijTYdu6uLZW9JISE2B4EevxzwDu9UGcJPHmJYi1rRQAP__jH97GiQC8FvkdAEfKqcwV9jAbBPQPG6lUkBLcoijgR3Bcwd-ta92oeZmcpoJ97PzzBbCL-NrppJ2HHQ1SMsYWoPveZTmZc66YBA0P9YfT4hZ0RQiP2gxB4snTvMFI0Ot6Q2nQ0p5DMxmWqIaCKW53rqn16AVXQeqC2TJjlbjA9sC6pr8GEGY2OQUgEmWu5GmnOSz1lNY7fNHJypChnieI_hyYiy06qouUpoHA5z_IUtfzZoMIG0yJiGUUpF9BJvYChDECCqaUM1kWnO5tKcohSKq5Hqwu_EWDRYF2tj7igSimZkS4Pts41tu8nIaVk5EkzAX9gCR2EX3Lk869mIxSyBS3MyG_NotPcbm6uXDn_YkV5Z0HkxUxYRA9hIG-UhKhK3VOaHZP8GcQN8noOMa2CnPd208X6HOzlIlxs7SRbzppUs_fHN1eROglNy-2oJWGmo-xOy0Qd44TtY0S_bYhu6iH6inrx3-yncSrWFxEiYosvYJD4ZBSyrV4d6UsfeNSHYS0ODTsdPqz4SYTeloZbIx8XWz7fxLXlNyLr3s9tp-Q25f1vTIrmQL' # rubocop:disable Layout/LineLength
+      )
+
+      OpenSSL::PKey.read(pem)
+    end
+
+    let(:secured_json) do
+      JSON.parse(<<~JSON)
+        {
+          "@context": [
+            "https://www.w3.org/ns/credentials/v2",
+            "https://w3id.org/citizenship/v4rc1"
+          ],
+          "type": [
+            "VerifiableCredential",
+            "EmploymentAuthorizationDocumentCredential"
+          ],
+          "issuer": {
+            "id": "did:key:zDnaegE6RR3atJtHKwTRTWHsJ3kNHqFwv7n9YjTgmU7TyfU76",
+            "image": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVQIW2NgUPr/HwADaAIhG61j/AAAAABJRU5ErkJggg=="
+          },
+          "credentialSubject": {
+            "type": [
+              "Person",
+              "EmployablePerson"
+            ],
+            "givenName": "JOHN",
+            "additionalName": "JACOB",
+            "familyName": "SMITH",
+            "image": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVQIW2Ng+M/wHwAEAQH/7yMK/gAAAABJRU5ErkJggg==",
+            "gender": "Male",
+            "residentSince": "2015-01-01",
+            "birthCountry": "Bahamas",
+            "birthDate": "1999-07-17",
+            "employmentAuthorizationDocument": {
+              "type": "EmploymentAuthorizationDocument",
+              "identifier": "83627465",
+              "lprCategory": "C09",
+              "lprNumber": "999-999-999"
+            }
+          },
+          "name": "Employment Authorization Document",
+          "description": "Example Employment Authorization Document.",
+          "validFrom": "2019-12-03T00:00:00Z",
+          "validUntil": "2029-12-03T00:00:00Z",
+          "proof": {
+            "type": "DataIntegrityProof",
+            "cryptosuite": "mldsa44-jcs-2024",
+            "created": "2023-02-24T23:36:38Z",
+            "verificationMethod": "did:key:ukCRKDtY8Do_dXzYGyuX7BY-1dDYM4FuSiw0gFdO-eJXFH0eqlt4_CP4sEISGAzNlKDzLpUJWoInRywXOpd7FCp_QAJAlL7iRo4cepKhzhlq8xt6qd5jkhYF9tNH8z3RGDl9aunNy_06fWLYNScWd5RmGg46Po8T-kIjMMkJftaqqZcGDxktpu9Et2bnaZMx4K98YyG1urUpM9lgvldgg2qv-6XCrm2uXlJ9U-HN4xtQKn4Ug-5xPwbhPGR2pbcBScTFotkhBqLc2eQLL6zPutWF83sSZbOhD_11BjMkeiLyJbMeHCIhz5GDIbPksEFIaSho3MdFo5fpQ8QZoqCit3Jn4ddfuShfIoLU1Hw5EZ0xBiqOU7e-TINd7-7HsgHLmYMGnpqljm1ot3c3cfalYsg87WQuSscO7XNH3Ewa-cgU6Bnj1SGn0plTy6Yq-GxU8XUBPwsK_IoIJbXWC0UD97c9UYpNiZi0-ECnbB-Y5_SM8auMfoIeap_buAOdXlJZmcp8xNCXI59AN9-96Sdhks5L-JmsELzyjAgjqNx8Zt3KPFc2jSwNjDVC1fEa8FdDdDT3WNkF6KTt65lb5_aIkFh20nOvT7kIJcKTgmhRGNJZgGSPYVbMypaQoaac8dtEoQjvYgnO-rM_RcsiWMHNc29br3o5wdiLXdr63MoX1lEWu_THBfeP1JuxrSbUmHOByepWbubbSM4iVQITCxBHZT0Mj2bWwIxd3nZUajzebyEnsfitV01kpzlO7bzY2uxSzyplTkRfppc_7YH0y0PHaggw0cIXNSh73wVqNZmzmJx5W0_akrvy5oSz9ZB1Io2p_fTxzibefwO700bUqbElV_yuCjD7EJ_Hfqbog80y_g9TK6koX7wYwqFNQxBVavKC-HbcT7yPdvzs9hlC2MNWCT3W7gVgeYr4AFgbV9EgMcH0GtJDKYw8vkpB_vTsaSTGZAj3TNKalAwiGO50VAmF5tknF96kOrWmNL0MdkXhnm1vXgDpP68bMt4r2Qr-hNdJ4s3_nqmSDYTnZRA4qjXjrgKQfO19txt0tX7LifE1GZ1bQyS7NqHWXyMEhw6_F8pc_tS16VhvJO_FM7CX51mLLkLCGl7DsmbnEIsVUW9qlCxb6bj53UyijTYdu6uLZW9JISE2B4EevxzwDu9UGcJPHmJYi1rRQAP__jH97GiQC8FvkdAEfKqcwV9jAbBPQPG6lUkBLcoijgR3Bcwd-ta92oeZmcpoJ97PzzBbCL-NrppJ2HHQ1SMsYWoPveZTmZc66YBA0P9YfT4hZ0RQiP2gxB4snTvMFI0Ot6Q2nQ0p5DMxmWqIaCKW53rqn16AVXQeqC2TJjlbjA9sC6pr8GEGY2OQUgEmWu5GmnOSz1lNY7fNHJypChnieI_hyYiy06qouUpoHA5z_IUtfzZoMIG0yJiGUUpF9BJvYChDECCqaUM1kWnO5tKcohSKq5Hqwu_EWDRYF2tj7igSimZkS4Pts41tu8nIaVk5EkzAX9gCR2EX3Lk869mIxSyBS3MyG_NotPcbm6uXDn_YkV5Z0HkxUxYRA9hIG-UhKhK3VOaHZP8GcQN8noOMa2CnPd208X6HOzlIlxs7SRbzppUs_fHN1eROglNy-2oJWGmo-xOy0Qd44TtY0S_bYhu6iH6inrx3-yncSrWFxEiYosvYJD4ZBSyrV4d6UsfeNSHYS0ODTsdPqz4SYTeloZbIx8XWz7fxLXlNyLr3s9tp-Q25f1vTIrmQL",
+            "proofPurpose": "assertionMethod",
+            "proofValue": "uTSucVLvXmOpmjGGNB-B9rM-u4HzBxN8ZIuZbpTHrjOTNBnahoE4PSdkeD-IzLLXykJn0aYq_APExy-Ka0BcJNMvKgkdjbbP33WmUwkzljno3szRUDrN9KX2DMH7j0iOBakU4ByjD-hTSO1iR6rlxsZPHJM1H-WLMhzVSggBILAuglItzstl663Gz5bFjEfbKAgfe50L4v4PjLFSDbJYcg65GtCKRXISkWrnJRuToWwvTVdcnIBOQwPBFKsvApPJMKrUTkIuZf4-V1uJ81zzct4o20O-DqLQ5bHfOR2n5Y4DSy6e5zg0-S3ADKtMtuPaQ8cAPUTEKRXGRQnSndnrtgMh2dimvpSaaw0TDy7zY6vrDxJa1tkrS0ulKf3Xz8xsNrNIkx4SaKYWPTjhRvdKqjdrpbGRt3mRSFFc0VE8vK44F_EVFIhwouL-4Rm4mXU2QkiO0YkwuAJM-QdWUACqzJ7TSf2QrrU8zAwOLbrGS5uZ1qLGD1PcgWfg2d0zTAYmcWP4LP63fTnFxwr-L0N_3MLFXixHNEp5osMlo2lhl5noDCmQpqCgluxkd5gXs1NSpOBbWVQyYWcj0WMBtMam8AeqXpA39L7oqvYxqbEpiwvKrmHsXIEZrnsHKCk2P0yc10AFCCtsIapvTHwIAjbDhX11HFU5cci4X5vCdG2BUzRsgmGeiYiUClCHmqsBW4z2GA9r0d9jtHZ03nMie_qS95XPsXuAFqypsP1HOfcIUAHHS9Wn4XGFz3hXoqMsmoUGRg9vEpC2j_nkcYZQphYLs54veWq5BBzoMqPuvYhhRdawdCnn-LTf7AxQgVGoRTpTy4IkXxr_pC1LUJZJkdKeG-2TuQzyHSkbMPu3YbWsGy2KxdGeFN2yUI8TTQ-MFHl-_jDCRBrAYyCVOgML4NAtbGqvs7h2tGZYI-m9MfjG0vjp7CUyIPD8BV-Yhku_bHd0hcrseKtYYyUjxISf2wveo4dfQ2AnCVdDAbBmznjPIDlkqx0316sRc-vXJGRQmfXOW1dNk-7WNBrJVQbnT9m6cf0UEl3mEgagk1_lLOxTgjzZRpWcOB827VB3hPi7RdI6U6knXuOflHPt9BZN7i6OAl76k69uMFH2KNH3Abm0GDhOv_nu1lEaOH8aXdOqL3U8Yo0cp5roOoTw5fJP2gxwI3DY0TOWeNOCfLXmnodgoGaKG2Vns4_-gN_Mg7g0ZinguwJMwKACx07H__ffh8jYQdc87EjCNyH4m8hJICvcC81J7CKb89YTZm7IM0D1_qTR5t-DkuU4ypxNuFOCxWpN9y2QiLAAobDdc1Y_S3nXFFkLmsn7hUNhcgXxPC3jLifiM0IV7DAqmQpk2ZGE59l0VTKb3F2Ualj9JcqKtLg_b2KqprUol9WtjFlkbxqJPYyCKnSEitzDnDsfxTRFEIViTx5-1SFb0NjPE_hv5MewCkizNpfo0b-m-FxvyWJnDYt4Igv8JtgF0K_xMRC9Tf3NaQgFHb1OgkBz04C3wsxoPLqTgMWoxcZ2-2x7TRRvX2Nh1Ye-ZrpmF5hVeRMK0ECj_t5HLPaq2md18rqnhwsZv84-V0eReDyXVIhkE2eAKedCM9t13UjTfF1qFoUQ3D8xQ6MfR7zFwf6X78Tb0EFs0cBQ1TatzWysbE2b_0k-YbT78G4Ko8FlmTljBN1b0StKxzOE1Kp1h4nDBY9jZYYPNnVrtAGn2AKN3HWr0bhhF8fW_G4SA_MGu2r6LnobB3MLCSj1lbVZSk5YtCtMnkldAsDagoI8lRBlKW1R7PFvXatSHcwbe352nVuvZYxs9QJVSylf2QS1xeUQUMS4AHd4h8Y9HqmnGPr5JX65uch8sr1bWcpGiNlwnMlFy89pnEZU2v7IiC_foLi8JbxMud1k2XRDwThhepEf5bxqlBcgjF8vAbGEKAJg5Oahl0GCBffuHhuUXmuF6XwOxLovlJUM8oFCTayQL42NGz_Z2cuFltmiy-cbI8NmEpvlOPnGZBj00ZIrp9tAgwepYvlt5ticFn9ufU-f8xZpBpZb-rf5sVTNqYmoOYvhKVhE5cCPpCbzZ5GvW5ukB8yLLJC5sc6df9oSoujovfA_VAXqsvmBuKU4cHcNTNEqzsGEg_l0ln5FIHKH3CRUTDemKN2vbtmTz1snn4VfdBFAlhJhBItpBmd3HibH-1q2WD313j-cE5nW_QgQeDn_JFJ7zwlORQVRUkeB942HJjkHWXCJMXz9LKxdncKalaVNm-yVjDkQdgA1tKl9bc_QnAL7HWhtHFc_XhzJvQxqLJ0aLUkkrnphrqscG6D_Kdh7aTTkDjDSA-dmgRQBh51YVBnfnp5V28AwmGXXglBAWCWChGmAtac6xeLbxW143426J4HMAUIpLgNhjetQoQqKzVTIpzcyo-GK8L3C0calt57orTswSRqDjxg_6zAQ6RPNoThToRqb2QgHr-gOop6NEJkEy0K8GwPg3nYAFgVVjcCyDtMEbIrHXJ9WKg3oTd14eC7GNZgQ75aP3HpUAqT5gqWdxer35Ohs3n1FylwreS1kOZ5Z4OVW5PVJkNHhKPfaNq4mQT5vBAWlWphOotPHwTbN7oMiOGYu-AMTnsLPCn0A3VEXx16EROpu0zlVisEZo1sya8nQaJYiI_i3MEWqvV2ypvcMDYt_ArFjxMU3tjV5tNcJgIoE5E5UCGyo2HQMvN03T0GdHZr7txswg9HpRJqntiJzm0iAr9BhRPfErg4HLQyc92gOH6UdczP4hvbweP3mcW67yUT3lH31vznZ5lIJ0pth3H_7khwUff5daIROar2usWxoMWTItY5HC7v5HBjnfqj4EoVi1A4Uw7RvHhaCMkfDrqqntNM0TDDSfDP1uCB1RwZtcuWpNfLWYyP1B9XqwKg3EworHhIq1vI74gZROvebyYqx8UCFeiLubTfXHJrC2evT99ha6jf7vg8zKgew6Cj3Jz_RSRE5rF5uQQno6PsevbKKtZsQmn0PQphfNzWqacMpred2yrmetGOEG_JvYxx5Scmu8w8Yg-3V7yhMeDsOh0DZ8sjTw5d-w3zKUNeU2IZzz5wvaJ7-8RRxyJqxFsUFaBv7WxUZ0bmWg4pRXdBUKNW53mEUGDigpRF6Fla-6wc4BCDhwfJWdpaixu8Lf4fkRKCs0Y4-lrsTH1-zwNkKBudbd6v4AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAwbKDA"
+          }
+        }
+      JSON
+    end
+
+    context 'with a correct signature' do
+      it 'verifies correctly' do
+        expect(described_class.verify_mldsa44_jcs_2024(secured_json, keypair)).to be true
+      end
+    end
+
+    context 'with an incorrect signature' do
+      let(:keypair) { OpenSSL::PKey.generate_key('ml-dsa-44') }
+
+      it 'does not verify document' do
+        expect(described_class.verify_mldsa44_jcs_2024(secured_json, keypair)).to be false
+      end
+    end
+  end
 end