JSON for Hash now has to be Base16

Fix #14532. As discussed on the call today: 1. We'll stick with `format = "base16"` and `hash = "<hash>"`, not do `base16 = "<hash>"`, in order to be forward compatible with supporting more versioning formats. The motivation we discussed for someday *possibly* doing this is making it easier to write very slap-dash lang2nix tools that create (not consume) derivations with dynamic derivations. 2. We will remove support for non-base16 (and make that the default, not base64) in `Hash`, so this is strictly forward contingency, *not* yet something we support. (And also not something we have concrete plans to start supporting.)
2025-12-12 20:11:03 +01:00 · 2025-11-10 16:07:28 -05:00 · 2025-11-10 16:07:28 -05:00 · bec3c5cfcd
commit bec3c5cfcd
parent 5b95745bc9
36 changed files with 141 additions and 162 deletions
--- a/src/json-schema-checks/meson.build
+++ b/src/json-schema-checks/meson.build
@ -32,10 +32,8 @@ schemas = [
    'stem' : 'hash',
    'schema' : schema_dir / 'hash-v1.yaml',
    'files' : [
-      'sha256-base64.json',
      'sha256-base16.json',
-      'sha256-nix32.json',
-      'blake3-base64.json',
+      'blake3-base16.json',
    ],
  },
  {
--- a/src/libstore-tests/data/common-protocol/content-address.json
+++ b/src/libstore-tests/data/common-protocol/content-address.json
@ -2,24 +2,24 @@
  {
    "hash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "+Xc9Ll6mcPltwaewrk/BAQ56Y3G5T//wzhKUc0zrYu0="
+      "format": "base16",
+      "hash": "f9773d2e5ea670f96dc1a7b0ae4fc1010e7a6371b94ffff0ce1294734ceb62ed"
    },
    "method": "text"
  },
  {
    "hash": {
      "algorithm": "sha1",
-      "format": "base64",
-      "hash": "gGemBoenViNZM3hiwqns/Fgzqwo="
+      "format": "base16",
+      "hash": "8067a60687a7562359337862c2a9ecfc5833ab0a"
    },
    "method": "flat"
  },
  {
    "hash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+      "format": "base16",
+      "hash": "10c209fa0890fe02c85a8c663ca8e7a37cc766bc5b1b29a0cc61b266f64121d3"
    },
    "method": "nar"
  }
--- a/src/libstore-tests/data/common-protocol/optional-content-address.json
+++ b/src/libstore-tests/data/common-protocol/optional-content-address.json
@ -3,8 +3,8 @@
  {
    "hash": {
      "algorithm": "sha1",
-      "format": "base64",
-      "hash": "gGemBoenViNZM3hiwqns/Fgzqwo="
+      "format": "base16",
+      "hash": "8067a60687a7562359337862c2a9ecfc5833ab0a"
    },
    "method": "flat"
  }
--- a/src/libstore-tests/data/content-address/nar.json
+++ b/src/libstore-tests/data/content-address/nar.json
@ -1,8 +1,8 @@
 {
  "hash": {
    "algorithm": "sha256",
-    "format": "base64",
-    "hash": "9vLqj0XYoFfJVmoz+ZR02i5camYE1zYSFlDicwxvsKM="
+    "format": "base16",
+    "hash": "f6f2ea8f45d8a057c9566a33f99474da2e5c6a6604d736121650e2730c6fb0a3"
  },
  "method": "nar"
 }
--- a/src/libstore-tests/data/content-address/text.json
+++ b/src/libstore-tests/data/content-address/text.json
@ -1,8 +1,8 @@
 {
  "hash": {
    "algorithm": "sha256",
-    "format": "base64",
-    "hash": "8OTC92xYkW7CWPJGhRvqCR0U1CR6L8PhhpRGGxgW4Ts="
+    "format": "base16",
+    "hash": "f0e4c2f76c58916ec258f246851bea091d14d4247a2fc3e18694461b1816e13b"
  },
  "method": "text"
 }
--- a/src/libstore-tests/data/derivation/output-caFixedFlat.json
+++ b/src/libstore-tests/data/derivation/output-caFixedFlat.json
@ -1,8 +1,8 @@
 {
  "hash": {
    "algorithm": "sha256",
-    "format": "base64",
-    "hash": "iUUXyRY8iW7DGirb0zwGgf1fRbLA7wimTJKgP7l/OQ8="
+    "format": "base16",
+    "hash": "894517c9163c896ec31a2adbd33c0681fd5f45b2c0ef08a64c92a03fb97f390f"
  },
  "method": "flat"
 }
--- a/src/libstore-tests/data/derivation/output-caFixedNAR.json
+++ b/src/libstore-tests/data/derivation/output-caFixedNAR.json
@ -1,8 +1,8 @@
 {
  "hash": {
    "algorithm": "sha256",
-    "format": "base64",
-    "hash": "iUUXyRY8iW7DGirb0zwGgf1fRbLA7wimTJKgP7l/OQ8="
+    "format": "base16",
+    "hash": "894517c9163c896ec31a2adbd33c0681fd5f45b2c0ef08a64c92a03fb97f390f"
  },
  "method": "nar"
 }
--- a/src/libstore-tests/data/derivation/output-caFixedText.json
+++ b/src/libstore-tests/data/derivation/output-caFixedText.json
@ -1,8 +1,8 @@
 {
  "hash": {
    "algorithm": "sha256",
-    "format": "base64",
-    "hash": "iUUXyRY8iW7DGirb0zwGgf1fRbLA7wimTJKgP7l/OQ8="
+    "format": "base16",
+    "hash": "894517c9163c896ec31a2adbd33c0681fd5f45b2c0ef08a64c92a03fb97f390f"
  },
  "method": "text"
 }
--- a/src/libstore-tests/data/dummy-store/one-flat-file.json
+++ b/src/libstore-tests/data/dummy-store/one-flat-file.json
@ -14,16 +14,16 @@
        "ca": {
          "hash": {
            "algorithm": "sha256",
-            "format": "base64",
-            "hash": "f1eduuSIYC1BofXA1tycF79Ai2NSMJQtUErx5DxLYSU="
+            "format": "base16",
+            "hash": "7f579dbae488602d41a1f5c0d6dc9c17bf408b635230942d504af1e43c4b6125"
          },
          "method": "nar"
        },
        "deriver": null,
        "narHash": {
          "algorithm": "sha256",
-          "format": "base64",
-          "hash": "f1eduuSIYC1BofXA1tycF79Ai2NSMJQtUErx5DxLYSU="
+          "format": "base16",
+          "hash": "7f579dbae488602d41a1f5c0d6dc9c17bf408b635230942d504af1e43c4b6125"
        },
        "narSize": 120,
        "references": [],
--- a/src/libstore-tests/data/nar-info/impure.json
+++ b/src/libstore-tests/data/nar-info/impure.json
@ -2,8 +2,8 @@
  "ca": {
    "hash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+      "format": "base16",
+      "hash": "10c209fa0890fe02c85a8c663ca8e7a37cc766bc5b1b29a0cc61b266f64121d3"
    },
    "method": "nar"
  },
@ -11,14 +11,14 @@
  "deriver": "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
  "downloadHash": {
    "algorithm": "sha256",
-    "format": "base64",
-    "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    "format": "base16",
+    "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
  },
  "downloadSize": 4029176,
  "narHash": {
    "algorithm": "sha256",
-    "format": "base64",
-    "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    "format": "base16",
+    "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
  },
  "narSize": 34878,
  "references": [
--- a/src/libstore-tests/data/nar-info/pure.json
+++ b/src/libstore-tests/data/nar-info/pure.json
@ -2,15 +2,15 @@
  "ca": {
    "hash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+      "format": "base16",
+      "hash": "10c209fa0890fe02c85a8c663ca8e7a37cc766bc5b1b29a0cc61b266f64121d3"
    },
    "method": "nar"
  },
  "narHash": {
    "algorithm": "sha256",
-    "format": "base64",
-    "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    "format": "base16",
+    "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
  },
  "narSize": 34878,
  "references": [
--- a/src/libstore-tests/data/path-info/empty_impure.json
+++ b/src/libstore-tests/data/path-info/empty_impure.json
@ -3,8 +3,8 @@
  "deriver": null,
  "narHash": {
    "algorithm": "sha256",
-    "format": "base64",
-    "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    "format": "base16",
+    "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
  },
  "narSize": 0,
  "references": [],
--- a/src/libstore-tests/data/path-info/empty_pure.json
+++ b/src/libstore-tests/data/path-info/empty_pure.json
@ -2,8 +2,8 @@
  "ca": null,
  "narHash": {
    "algorithm": "sha256",
-    "format": "base64",
-    "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    "format": "base16",
+    "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
  },
  "narSize": 0,
  "references": [],
--- a/src/libstore-tests/data/path-info/impure.json
+++ b/src/libstore-tests/data/path-info/impure.json
@ -2,16 +2,16 @@
  "ca": {
    "hash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+      "format": "base16",
+      "hash": "10c209fa0890fe02c85a8c663ca8e7a37cc766bc5b1b29a0cc61b266f64121d3"
    },
    "method": "nar"
  },
  "deriver": "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
  "narHash": {
    "algorithm": "sha256",
-    "format": "base64",
-    "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    "format": "base16",
+    "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
  },
  "narSize": 34878,
  "references": [
--- a/src/libstore-tests/data/path-info/pure.json
+++ b/src/libstore-tests/data/path-info/pure.json
@ -2,15 +2,15 @@
  "ca": {
    "hash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+      "format": "base16",
+      "hash": "10c209fa0890fe02c85a8c663ca8e7a37cc766bc5b1b29a0cc61b266f64121d3"
    },
    "method": "nar"
  },
  "narHash": {
    "algorithm": "sha256",
-    "format": "base64",
-    "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+    "format": "base16",
+    "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
  },
  "narSize": 34878,
  "references": [
--- a/src/libstore-tests/data/serve-protocol/content-address.json
+++ b/src/libstore-tests/data/serve-protocol/content-address.json
@ -2,24 +2,24 @@
  {
    "hash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "+Xc9Ll6mcPltwaewrk/BAQ56Y3G5T//wzhKUc0zrYu0="
+      "format": "base16",
+      "hash": "f9773d2e5ea670f96dc1a7b0ae4fc1010e7a6371b94ffff0ce1294734ceb62ed"
    },
    "method": "text"
  },
  {
    "hash": {
      "algorithm": "sha1",
-      "format": "base64",
-      "hash": "gGemBoenViNZM3hiwqns/Fgzqwo="
+      "format": "base16",
+      "hash": "8067a60687a7562359337862c2a9ecfc5833ab0a"
    },
    "method": "flat"
  },
  {
    "hash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+      "format": "base16",
+      "hash": "10c209fa0890fe02c85a8c663ca8e7a37cc766bc5b1b29a0cc61b266f64121d3"
    },
    "method": "nar"
  }
--- a/src/libstore-tests/data/serve-protocol/optional-content-address.json
+++ b/src/libstore-tests/data/serve-protocol/optional-content-address.json
@ -3,8 +3,8 @@
  {
    "hash": {
      "algorithm": "sha1",
-      "format": "base64",
-      "hash": "gGemBoenViNZM3hiwqns/Fgzqwo="
+      "format": "base16",
+      "hash": "8067a60687a7562359337862c2a9ecfc5833ab0a"
    },
    "method": "flat"
  }
--- a/src/libstore-tests/data/serve-protocol/unkeyed-valid-path-info-2.3.json
+++ b/src/libstore-tests/data/serve-protocol/unkeyed-valid-path-info-2.3.json
@ -4,8 +4,8 @@
    "deriver": null,
    "narHash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA="
+      "format": "base16",
+      "hash": "0000000000000000000000000000000000000000000000000000000000000000"
    },
    "narSize": 34878,
    "references": [],
@ -19,8 +19,8 @@
    "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
    "narHash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA="
+      "format": "base16",
+      "hash": "0000000000000000000000000000000000000000000000000000000000000000"
    },
    "narSize": 34878,
    "references": [
--- a/src/libstore-tests/data/serve-protocol/unkeyed-valid-path-info-2.4.json
+++ b/src/libstore-tests/data/serve-protocol/unkeyed-valid-path-info-2.4.json
@ -4,8 +4,8 @@
    "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
    "narHash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+      "format": "base16",
+      "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
    },
    "narSize": 34878,
    "references": [
@ -20,16 +20,16 @@
    "ca": {
      "hash": {
        "algorithm": "sha256",
-        "format": "base64",
-        "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+        "format": "base16",
+        "hash": "10c209fa0890fe02c85a8c663ca8e7a37cc766bc5b1b29a0cc61b266f64121d3"
      },
      "method": "nar"
    },
    "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
    "narHash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+      "format": "base16",
+      "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
    },
    "narSize": 34878,
    "references": [
--- a/src/libstore-tests/data/worker-protocol/content-address.json
+++ b/src/libstore-tests/data/worker-protocol/content-address.json
@ -2,24 +2,24 @@
  {
    "hash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "+Xc9Ll6mcPltwaewrk/BAQ56Y3G5T//wzhKUc0zrYu0="
+      "format": "base16",
+      "hash": "f9773d2e5ea670f96dc1a7b0ae4fc1010e7a6371b94ffff0ce1294734ceb62ed"
    },
    "method": "text"
  },
  {
    "hash": {
      "algorithm": "sha1",
-      "format": "base64",
-      "hash": "gGemBoenViNZM3hiwqns/Fgzqwo="
+      "format": "base16",
+      "hash": "8067a60687a7562359337862c2a9ecfc5833ab0a"
    },
    "method": "flat"
  },
  {
    "hash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+      "format": "base16",
+      "hash": "10c209fa0890fe02c85a8c663ca8e7a37cc766bc5b1b29a0cc61b266f64121d3"
    },
    "method": "nar"
  }
--- a/src/libstore-tests/data/worker-protocol/optional-content-address.json
+++ b/src/libstore-tests/data/worker-protocol/optional-content-address.json
@ -3,8 +3,8 @@
  {
    "hash": {
      "algorithm": "sha1",
-      "format": "base64",
-      "hash": "gGemBoenViNZM3hiwqns/Fgzqwo="
+      "format": "base16",
+      "hash": "8067a60687a7562359337862c2a9ecfc5833ab0a"
    },
    "method": "flat"
  }
--- a/src/libstore-tests/data/worker-protocol/unkeyed-valid-path-info-1.15.json
+++ b/src/libstore-tests/data/worker-protocol/unkeyed-valid-path-info-1.15.json
@ -4,8 +4,8 @@
    "deriver": null,
    "narHash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+      "format": "base16",
+      "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
    },
    "narSize": 34878,
    "references": [],
@ -19,8 +19,8 @@
    "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
    "narHash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+      "format": "base16",
+      "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
    },
    "narSize": 34878,
    "references": [
--- a/src/libstore-tests/data/worker-protocol/valid-path-info-1.15.json
+++ b/src/libstore-tests/data/worker-protocol/valid-path-info-1.15.json
@ -4,8 +4,8 @@
    "deriver": null,
    "narHash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+      "format": "base16",
+      "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
    },
    "narSize": 34878,
    "path": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
@ -20,8 +20,8 @@
    "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
    "narHash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+      "format": "base16",
+      "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
    },
    "narSize": 34878,
    "path": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
--- a/src/libstore-tests/data/worker-protocol/valid-path-info-1.16.json
+++ b/src/libstore-tests/data/worker-protocol/valid-path-info-1.16.json
@ -4,8 +4,8 @@
    "deriver": null,
    "narHash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+      "format": "base16",
+      "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
    },
    "narSize": 34878,
    "path": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
@ -20,8 +20,8 @@
    "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
    "narHash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+      "format": "base16",
+      "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
    },
    "narSize": 34878,
    "path": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
@ -41,16 +41,16 @@
    "ca": {
      "hash": {
        "algorithm": "sha256",
-        "format": "base64",
-        "hash": "EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM="
+        "format": "base16",
+        "hash": "10c209fa0890fe02c85a8c663ca8e7a37cc766bc5b1b29a0cc61b266f64121d3"
      },
      "method": "nar"
    },
    "deriver": null,
    "narHash": {
      "algorithm": "sha256",
-      "format": "base64",
-      "hash": "FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc="
+      "format": "base16",
+      "hash": "15e3c560894cbb27085cf65b5a2ecb18488c999497f4531b6907a7581ce6d527"
    },
    "narSize": 34878,
    "path": "n5wkd9frr45pa74if5gpz9j7mifg27fh-foo",
--- a/src/libutil-tests/data/hash/blake3-base16.json
+++ b/src/libutil-tests/data/hash/blake3-base16.json
@ -0,0 +1,5 @@
+{
+  "algorithm": "blake3",
+  "format": "base16",
+  "hash": "9e70ee1449965fb62d049040a1ed06ec377430da6ec13173e7c4fffcd28be980"
+}
--- a/src/libutil-tests/data/hash/blake3-base64.json
+++ b/src/libutil-tests/data/hash/blake3-base64.json
@ -1,5 +0,0 @@
-{
-  "algorithm": "blake3",
-  "format": "base64",
-  "hash": "nnDuFEmWX7YtBJBAoe0G7Dd0MNpuwTFz58T//NKL6YA="
-}
--- a/src/libutil-tests/data/hash/sha256-base16.json
+++ b/src/libutil-tests/data/hash/sha256-base16.json
@ -1,5 +1,5 @@
 {
-    "algorithm": "sha256",
-    "format": "base16",
-    "hash": "f0e4c2f76c58916ec258f246851bea091d14d4247a2fc3e18694461b1816e13b"
+  "algorithm": "sha256",
+  "format": "base16",
+  "hash": "f0e4c2f76c58916ec258f246851bea091d14d4247a2fc3e18694461b1816e13b"
 }
--- a/src/libutil-tests/data/hash/simple.json
+++ b/src/libutil-tests/data/hash/simple.json
@ -1,5 +1,5 @@
 {
  "algorithm": "sha256",
-  "format": "base64",
-  "hash": "8OTC92xYkW7CWPJGhRvqCR0U1CR6L8PhhpRGGxgW4Ts="
+  "format": "base16",
+  "hash": "f0e4c2f76c58916ec258f246851bea091d14d4247a2fc3e18694461b1816e13b"
 }
--- a/src/libutil-tests/hash.cc
+++ b/src/libutil-tests/hash.cc
@ -215,9 +215,7 @@ struct HashJsonTest : virtual HashTest,
                      ::testing::WithParamInterface<std::pair<std::string_view, Hash>>
 {};

-struct HashJsonParseOnlyTest : virtual HashTest,
-                               JsonCharacterizationTest<Hash>,
-                               ::testing::WithParamInterface<std::pair<std::string_view, Hash>>
+struct HashJsonParseFailureTest : virtual HashTest, ::testing::WithParamInterface<std::string_view>
 {};

 struct BLAKE3HashJsonTest : virtual HashTest,
@ -238,10 +236,12 @@ TEST_P(HashJsonTest, to_json)
    writeJsonTest(name, value);
 }

-TEST_P(HashJsonParseOnlyTest, from_json)
+TEST_P(HashJsonParseFailureTest, from_json)
 {
-    auto & [name, expected] = GetParam();
-    readJsonTest(name, expected);
+    auto & name = GetParam();
+    auto path = goldenMaster(Path{name} + ".json");
+    auto encoded = json::parse(readFile(path));
+    ASSERT_THROW(nlohmann::adl_serializer<Hash>::from_json(encoded), Error);
 }

 TEST_P(BLAKE3HashJsonTest, from_json)
@ -256,8 +256,8 @@ TEST_P(BLAKE3HashJsonTest, to_json)
    writeJsonTest(name, expected);
 }

-// Round-trip tests (from_json + to_json) for base64 format only
-// (to_json always outputs base64)
+// Round-trip tests (from_json + to_json) for base16 format only
+// (to_json always outputs base16)
 INSTANTIATE_TEST_SUITE_P(
    HashJSON,
    HashJsonTest,
@ -266,32 +266,22 @@ INSTANTIATE_TEST_SUITE_P(
            "simple",
            hashString(HashAlgorithm::SHA256, "asdf"),
        },
-        std::pair{
-            "sha256-base64",
-            hashString(HashAlgorithm::SHA256, "asdf"),
-        }));
-
-// Parse-only tests for non-base64 formats
-// These verify C++ can deserialize other formats correctly
-INSTANTIATE_TEST_SUITE_P(
-    HashJSONParseOnly,
-    HashJsonParseOnlyTest,
-    ::testing::Values(
        std::pair{
            "sha256-base16",
            hashString(HashAlgorithm::SHA256, "asdf"),
-        },
-        std::pair{
-            "sha256-nix32",
-            hashString(HashAlgorithm::SHA256, "asdf"),
        }));

-INSTANTIATE_TEST_SUITE_P(BLAKE3HashJSONParseOnly, BLAKE3HashJsonTest, ([] {
+// Failure tests for unsupported formats (base64, nix32, sri)
+// These verify that non-base16 formats are rejected
+INSTANTIATE_TEST_SUITE_P(
+    HashJSONParseFailure, HashJsonParseFailureTest, ::testing::Values("sha256-base64", "sha256-nix32"));
+
+INSTANTIATE_TEST_SUITE_P(BLAKE3HashJSON, BLAKE3HashJsonTest, ([] {
                             ExperimentalFeatureSettings mockXpSettings;
                             mockXpSettings.set("experimental-features", "blake3-hashes");
                             return ::testing::Values(
                                 std::pair{
-                                     "blake3-base64",
+                                     "blake3-base16",
                                     hashString(HashAlgorithm::BLAKE3, "asdf", mockXpSettings),
                                 });
                         }()));
--- a/src/libutil/hash.cc
+++ b/src/libutil/hash.cc
@ -508,7 +508,14 @@ Hash adl_serializer<Hash>::from_json(const json & json, const ExperimentalFeatur
 {
    auto & obj = getObject(json);
    auto algo = parseHashAlgo(getString(valueAt(obj, "algorithm")), xpSettings);
-    auto format = parseHashFormat(getString(valueAt(obj, "format")));
+    auto formatStr = getString(valueAt(obj, "format"));
+    auto format = parseHashFormat(formatStr);
+
+    // Only base16 format is supported for JSON serialization
+    if (format != HashFormat::Base16) {
+        throw Error("hash format '%s' is not supported in JSON; only 'base16' is currently supported", formatStr);
+    }
+
    auto & hashS = getString(valueAt(obj, "hash"));
    return Hash::parseExplicitFormatUnprefixed(hashS, algo, format, xpSettings);
 }
@ -516,9 +523,9 @@ Hash adl_serializer<Hash>::from_json(const json & json, const ExperimentalFeatur
 void adl_serializer<Hash>::to_json(json & json, const Hash & hash)
 {
    json = {
-        {"format", printHashFormat(HashFormat::Base64)},
+        {"format", printHashFormat(HashFormat::Base16)},
        {"algorithm", printHashAlgo(hash.algo)},
-        {"hash", hash.to_string(HashFormat::Base64, false)},
+        {"hash", hash.to_string(HashFormat::Base16, false)},
    };
 }