diff --git a/Cargo.lock b/Cargo.lock
index 2cf0ca0..280f287 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -67,12 +67,45 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "autocfg"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
+
+[[package]]
+name = "base16ct"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4c7f02d4ea65f2c1853089ffd8d2787bdbc63de2f0d29dedbcf8ccdfa0ccd4cf"
+
+[[package]]
+name = "base64ct"
+version = "1.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8c3c1a368f70d6cf7302d78f8f7093da241fb8e8807c05cc9e51a125895a6d5b"
+
 [[package]]
 name = "bitflags"
 version = "2.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "327762f6e5a765692301e5bb513e0d9fef63be86bbc14528052b1cd3e6f03e07"
 
+[[package]]
+name = "block-buffer"
+version = "0.10.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3078c7629b62d3f0439517fa394996acacc5cbc91c5a20d8c658e77abd503a71"
+dependencies = [
+ "generic-array",
+]
+
+[[package]]
+name = "byteorder"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fd0f2584146f6f2ef48085050886acf353beff7305ebd1ae69500e27c67f64b"
+
 [[package]]
 name = "cc"
 version = "1.0.83"
@@ -83,6 +116,22 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "cipher"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "773f3b9af64447d2ce9850330c473515014aa235e6a783b02db81ff39e4a3dad"
+dependencies = [
+ "crypto-common",
+ "inout",
+]
+
 [[package]]
 name = "clap"
 version = "4.4.7"
@@ -143,12 +192,104 @@ dependencies = [
  "toml 0.5.11",
 ]
 
+[[package]]
+name = "const-oid"
+version = "0.9.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "28c122c3980598d243d63d9a704629a2d748d101f278052ff068be5a4423ab6f"
+
+[[package]]
+name = "cpufeatures"
+version = "0.2.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ce420fe07aecd3e67c5f910618fe65e94158f6dcc0adf44e00d69ce2bdfe0fd0"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "crypto-bigint"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "740fe28e594155f10cfc383984cbefd529d7396050557148f79cb0f621204124"
+dependencies = [
+ "generic-array",
+ "rand_core",
+ "subtle",
+ "zeroize",
+]
+
+[[package]]
+name = "crypto-common"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1bfb12502f3fc46cca1bb51ac28df9d618d813cdc3d2f25b9fe775a34af26bb3"
+dependencies = [
+ "generic-array",
+ "typenum",
+]
+
+[[package]]
+name = "der"
+version = "0.7.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fffa369a668c8af7dbf8b5e56c9f744fbd399949ed171606040001947de40b1c"
+dependencies = [
+ "const-oid",
+ "zeroize",
+]
+
 [[package]]
 name = "diff"
 version = "0.1.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "56254986775e3233ffa9c4d7d3faaf6d36a2c09d30b20687e9f88bc8bafc16c8"
 
+[[package]]
+name = "digest"
+version = "0.10.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
+dependencies = [
+ "block-buffer",
+ "const-oid",
+ "crypto-common",
+ "subtle",
+]
+
+[[package]]
+name = "ecdsa"
+version = "0.16.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a4b1e0c257a9e9f25f90ff76d7a68360ed497ee519c8e428d1825ef0000799d4"
+dependencies = [
+ "der",
+ "digest",
+ "elliptic-curve",
+ "rfc6979",
+ "signature",
+ "spki",
+]
+
+[[package]]
+name = "elliptic-curve"
+version = "0.13.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d97ca172ae9dc9f9b779a6e3a65d308f2af74e5b8c921299075bdb4a0370e914"
+dependencies = [
+ "base16ct",
+ "crypto-bigint",
+ "digest",
+ "ff",
+ "generic-array",
+ "group",
+ "pkcs8",
+ "rand_core",
+ "sec1",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "env_logger"
 version = "0.10.0"
@@ -176,6 +317,16 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "ff"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ded41244b729663b1e574f1b4fb731469f69f79c17667b5d776b16cda0479449"
+dependencies = [
+ "rand_core",
+ "subtle",
+]
+
 [[package]]
 name = "form_urlencoded"
 version = "1.2.0"
@@ -185,6 +336,28 @@ dependencies = [
  "percent-encoding",
 ]
 
+[[package]]
+name = "generic-array"
+version = "0.14.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85649ca51fd72272d7821adaf274ad91c288277713d9c18820d8499a7ff69e9a"
+dependencies = [
+ "typenum",
+ "version_check",
+ "zeroize",
+]
+
+[[package]]
+name = "getrandom"
+version = "0.2.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fe9006bed769170c11f845cf00c7c1e9092aeb3f268e007c3e760ac68008070f"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
 [[package]]
 name = "git2"
 version = "0.18.1"
@@ -200,6 +373,17 @@ dependencies = [
  "url",
 ]
 
+[[package]]
+name = "group"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f0f9ef7462f7c099f518d754361858f86d8a07af53ba9af0fe635bbccb151a63"
+dependencies = [
+ "ff",
+ "rand_core",
+ "subtle",
+]
+
 [[package]]
 name = "hashbrown"
 version = "0.14.2"
@@ -218,6 +402,15 @@ version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d77f7ec81a6d05a3abb01ab6eb7590f6083d08449fe5a1c8b1e620283546ccb7"
 
+[[package]]
+name = "hmac"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c49c37c09c17a53d937dfbb742eb3a961d65a994e6bcdcf37e7399d0cc8ab5e"
+dependencies = [
+ "digest",
+]
+
 [[package]]
 name = "home"
 version = "0.5.5"
@@ -247,6 +440,15 @@ dependencies = [
  "hashbrown",
 ]
 
+[[package]]
+name = "inout"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a0c10553d664a4d0bcff9f4215d0aac67a639cc68ef660840afe309b807bc9f5"
+dependencies = [
+ "generic-array",
+]
+
 [[package]]
 name = "is-terminal"
 version = "0.4.9"
@@ -272,6 +474,9 @@ name = "lazy_static"
 version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+dependencies = [
+ "spin",
+]
 
 [[package]]
 name = "libc"
@@ -293,6 +498,12 @@ dependencies = [
  "pkg-config",
 ]
 
+[[package]]
+name = "libm"
+version = "0.2.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4ec2a862134d2a7d32d7983ddcdd1c4923530833c9f2ea1a44fc5fa473989058"
+
 [[package]]
 name = "libssh2-sys"
 version = "0.3.0"
@@ -353,6 +564,54 @@ dependencies = [
  "minimal-lexical",
 ]
 
+[[package]]
+name = "num-bigint-dig"
+version = "0.8.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc84195820f291c7697304f3cbdadd1cb7199c0efc917ff5eafd71225c136151"
+dependencies = [
+ "byteorder",
+ "lazy_static",
+ "libm",
+ "num-integer",
+ "num-iter",
+ "num-traits",
+ "rand",
+ "smallvec",
+ "zeroize",
+]
+
+[[package]]
+name = "num-integer"
+version = "0.1.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "225d3389fb3509a24c93f5c29eb6bde2586b98d9f016636dff58d7c6f7569cd9"
+dependencies = [
+ "autocfg",
+ "num-traits",
+]
+
+[[package]]
+name = "num-iter"
+version = "0.1.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d03e6c028c5dc5cac6e2dec0efda81fc887605bb3d884578bb6d6bf7514e252"
+dependencies = [
+ "autocfg",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "39e3200413f237f41ab11ad6d161bc7239c84dcb631773ccd7de3dfe4b5c267c"
+dependencies = [
+ "autocfg",
+ "libm",
+]
+
 [[package]]
 name = "openssl-probe"
 version = "0.1.5"
@@ -381,24 +640,84 @@ dependencies = [
  "vcpkg",
 ]
 
+[[package]]
+name = "p256"
+version = "0.13.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c9863ad85fa8f4460f9c48cb909d38a0d689dba1f6f6988a5e3e0d31071bcd4b"
+dependencies = [
+ "ecdsa",
+ "elliptic-curve",
+ "primeorder",
+ "sha2",
+]
+
+[[package]]
+name = "p384"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "70786f51bcc69f6a4c0360e063a4cac5419ef7c5cd5b3c99ad70f3be5ba79209"
+dependencies = [
+ "ecdsa",
+ "elliptic-curve",
+ "primeorder",
+ "sha2",
+]
+
 [[package]]
 name = "pathdiff"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8835116a5c179084a830efb3adc117ab007512b535bc1a21c991d3b32a6b44dd"
 
+[[package]]
+name = "pem-rfc7468"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "88b39c9bfcfc231068454382784bb460aae594343fb030d46e9f50a645418412"
+dependencies = [
+ "base64ct",
+]
+
 [[package]]
 name = "percent-encoding"
 version = "2.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b2a4787296e9989611394c33f193f676704af1686e70b8f8033ab5ba9a35a94"
 
+[[package]]
+name = "pkcs1"
+version = "0.7.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c8ffb9f10fa047879315e6625af03c164b16962a5368d724ed16323b68ace47f"
+dependencies = [
+ "der",
+ "pkcs8",
+ "spki",
+]
+
+[[package]]
+name = "pkcs8"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f950b2377845cebe5cf8b5165cb3cc1a5e0fa5cfa3e1f7f55707d8fd82e0a7b7"
+dependencies = [
+ "der",
+ "spki",
+]
+
 [[package]]
 name = "pkg-config"
 version = "0.3.27"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "26072860ba924cbfa98ea39c8c19b4dd6a4a25423dbdf219c1eca91aa0cf6964"
 
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
 [[package]]
 name = "pretty_assertions"
 version = "1.4.0"
@@ -409,6 +728,15 @@ dependencies = [
  "yansi",
 ]
 
+[[package]]
+name = "primeorder"
+version = "0.13.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c7dbe9ed3b56368bd99483eb32fe9c17fdd3730aebadc906918ce78d54c7eeb4"
+dependencies = [
+ "elliptic-curve",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.69"
@@ -439,6 +767,7 @@ dependencies = [
  "project-root",
  "regex-lite",
  "serde",
+ "ssh-key",
  "thiserror",
  "toml 0.8.6",
 ]
@@ -452,12 +781,72 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
 [[package]]
 name = "regex-lite"
 version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "30b661b2f27137bdbc16f00eda72866a92bb28af1753ffbd56744fb6e2e9cd8e"
 
+[[package]]
+name = "rfc6979"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8dd2a808d456c4a54e300a23e9f5a67e122c3024119acbfd73e3bf664491cb2"
+dependencies = [
+ "hmac",
+ "subtle",
+]
+
+[[package]]
+name = "rsa"
+version = "0.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "86ef35bf3e7fe15a53c4ab08a998e42271eab13eb0db224126bc7bc4c4bad96d"
+dependencies = [
+ "const-oid",
+ "digest",
+ "num-bigint-dig",
+ "num-integer",
+ "num-traits",
+ "pkcs1",
+ "pkcs8",
+ "rand_core",
+ "sha2",
+ "signature",
+ "spki",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "rustix"
 version = "0.38.21"
@@ -471,6 +860,20 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "sec1"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d3e97a565f76233a6003f9f5c54be1d9c5bdfa3eccfb189469f11ec4901c47dc"
+dependencies = [
+ "base16ct",
+ "der",
+ "generic-array",
+ "pkcs8",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "serde"
 version = "1.0.190"
@@ -500,12 +903,101 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "sha2"
+version = "0.10.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "793db75ad2bcafc3ffa7c68b215fee268f537982cd901d132f89c6343f3a3dc8"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest",
+]
+
+[[package]]
+name = "signature"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5e1788eed21689f9cf370582dfc467ef36ed9c707f073528ddafa8d83e3b8500"
+dependencies = [
+ "digest",
+ "rand_core",
+]
+
+[[package]]
+name = "smallvec"
+version = "1.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "942b4a808e05215192e39f4ab80813e599068285906cc91aa64f923db842bd5a"
+
+[[package]]
+name = "spin"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e63cff320ae2c57904679ba7cb63280a3dc4613885beafb148ee7bf9aa9042d"
+
+[[package]]
+name = "spki"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9d1e996ef02c474957d681f1b05213dfb0abab947b446a62d37770b23500184a"
+dependencies = [
+ "base64ct",
+ "der",
+]
+
+[[package]]
+name = "ssh-cipher"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "caac132742f0d33c3af65bfcde7f6aa8f62f0e991d80db99149eb9d44708784f"
+dependencies = [
+ "cipher",
+ "ssh-encoding",
+]
+
+[[package]]
+name = "ssh-encoding"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eb9242b9ef4108a78e8cd1a2c98e193ef372437f8c22be363075233321dd4a15"
+dependencies = [
+ "base64ct",
+ "pem-rfc7468",
+ "sha2",
+]
+
+[[package]]
+name = "ssh-key"
+version = "0.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2180b3bc4955efd5661a97658d3cf4c8107e0d132f619195afe9486c13cca313"
+dependencies = [
+ "p256",
+ "p384",
+ "rand_core",
+ "rsa",
+ "sec1",
+ "sha2",
+ "signature",
+ "ssh-cipher",
+ "ssh-encoding",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "strsim"
 version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
 
+[[package]]
+name = "subtle"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "81cdd64d312baedb58e21336b31bc043b77e01cc99033ce76ef539f78e965ebc"
+
 [[package]]
 name = "syn"
 version = "2.0.38"
@@ -605,6 +1097,12 @@ dependencies = [
  "winnow",
 ]
 
+[[package]]
+name = "typenum"
+version = "1.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42ff0bf0c66b8238c6f3b578df37d0b7848e55df8577b3f74f92a69acceeb825"
+
 [[package]]
 name = "unicode-bidi"
 version = "0.3.13"
@@ -649,6 +1147,18 @@ 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 = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
@@ -760,3 +1270,9 @@ name = "yansi"
 version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "09041cd90cf85f7f8b2df60c646f853b7f535ce68f85244eb6731cf89fa498ec"
+
+[[package]]
+name = "zeroize"
+version = "1.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2a0956f1ba7c7909bfb66c2e9e4124ab6f6482560f6628b5aaeba39207c9aad9"
diff --git a/Cargo.toml b/Cargo.toml
index 68d1858..455f34b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,13 +18,14 @@ vendored-libgit2 = ["git2/vendored-libgit2"]
 [dependencies]
 anyhow = "1.0.75"
 clap = { version = "4.4.7", features = ["derive"] }
-config = { version = "0.13.3", default-features = false , features = ["toml"] }
+config = { version = "0.13.3", default-features = false, features = ["toml"] }
 env_logger = { version = "0.10.0", default-features = false, features = ["auto-color"] }
 git2 = "0.18.1"
 home = "0.5.5"
 log = "0.4.20"
 regex-lite = "0.1.5"
 serde = { version = "1.0.190", features = ["derive"] }
+ssh-key = "0.6.2"
 thiserror = "1.0.50"
 toml = { version = "0.8.6", features = ["preserve_order"] }
 
diff --git a/src/git/cache.rs b/src/git/cache.rs
index a1e8f2c..8784697 100644
--- a/src/git/cache.rs
+++ b/src/git/cache.rs
@@ -1,9 +1,11 @@
 use std::path::{Path, PathBuf};
 
 use git2::{
-    build::RepoBuilder, Config, Cred, CredentialType, FetchOptions, RemoteCallbacks, Repository,
+    build::RepoBuilder, cert::Cert, CertificateCheckStatus, Config, Cred, CredentialType,
+    FetchOptions, RemoteCallbacks, Repository,
 };
 use log::{info, trace};
+use ssh_key::{known_hosts::HostPatterns, KnownHosts};
 use thiserror::Error;
 
 use crate::{
@@ -12,6 +14,7 @@ use crate::{
 };
 
 const WORKTREES_DIR: &str = "dependencies";
+const GLOBAL_KNOWN_HOSTS: &str = "/etc/ssh/ssh_known_hosts";
 
 pub struct ProtofetchGitCache {
     location: PathBuf,
@@ -152,6 +155,8 @@ impl ProtofetchGitCache {
             Err(git2::Error::from_str("no valid authentication available"))
         });
 
+        callbacks.certificate_check(|certificate, host| self.check_certificate(certificate, host));
+
         let mut fetch_options = FetchOptions::new();
         fetch_options
             .remote_callbacks(callbacks)
@@ -159,4 +164,56 @@ impl ProtofetchGitCache {
 
         Ok(fetch_options)
     }
+
+    fn check_certificate(
+        &self,
+        certificate: &Cert<'_>,
+        host: &str,
+    ) -> Result<CertificateCheckStatus, git2::Error> {
+        if let Some(hostkey) = certificate.as_hostkey().and_then(|h| h.hostkey()) {
+            trace!("Loading {}", GLOBAL_KNOWN_HOSTS);
+            match KnownHosts::read_file(GLOBAL_KNOWN_HOSTS) {
+                Ok(entries) => {
+                    for entry in entries {
+                        if host_matches_patterns(host, entry.host_patterns()) {
+                            trace!(
+                                "Found known host entry for {} ({})",
+                                host,
+                                entry.public_key().algorithm()
+                            );
+                            if entry.public_key().to_bytes().as_deref() == Ok(hostkey) {
+                                trace!("Known host entry matches the host key");
+                                return Ok(CertificateCheckStatus::CertificateOk);
+                            }
+                        }
+                    }
+                    trace!("No know host entry matched the host key");
+                }
+                Err(error) => trace!("Could not load {}: {}", GLOBAL_KNOWN_HOSTS, error),
+            }
+        }
+        Ok(CertificateCheckStatus::CertificatePassthrough)
+    }
+}
+
+fn host_matches_patterns(host: &str, patterns: &HostPatterns) -> bool {
+    match patterns {
+        HostPatterns::Patterns(patterns) => {
+            let mut match_found = false;
+            for pattern in patterns {
+                let pattern = pattern.to_lowercase();
+                // * and ? wildcards are not yet supported
+                if let Some(pattern) = pattern.strip_prefix('!') {
+                    if pattern == host {
+                        return false;
+                    }
+                } else {
+                    match_found |= pattern == host;
+                }
+            }
+            match_found
+        }
+        // Not yet supported
+        HostPatterns::HashedName { .. } => false,
+    }
 }